<PAGE>

                                                                   Exhibit 99.12




                                    TERM LOAN

                                CREDIT AGREEMENT

                                      among

                         QUEST DIAGNOSTICS INCORPORATED

                                  as Borrower,

                                       AND

                      CERTAIN SUBSIDIARIES OF THE BORROWER

                                 as Guarantors,

                                       AND

                         THE LENDERS IDENTIFIED HEREIN,

                                       AND

                             BANK OF AMERICA, N.A.,

                             as Administrative Agent

                                       AND

                              MERRILL LYNCH & CO.,
               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED

                              as Syndication Agent

                                       AND

                      WACHOVIA BANK, NATIONAL ASSOCIATION,
                          DEUTSCHE BANK SECURITIES INC.

                                       AND

                              THE BANK OF NEW YORK

                           as Co-Documentation Agents

                            DATED AS OF JUNE 21, 2002


                         BANC OF AMERICA SECURITIES LLC

                                       AND

                              MERRILL LYNCH & CO.,

               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED

                  as Joint Book Managers and Co-Lead Arrangers
<PAGE>
                                TABLE OF CONTENTS


<TABLE>
<S>                                                                                                                <C>
SECTION 1  DEFINITIONS AND ACCOUNTING TERMS......................................................................   1
         1.1    Definitions......................................................................................   1
         1.2    Computation of Time Periods and Other Definitional Provisions....................................  23
         1.3    Accounting Terms/Calculation of Financial Covenants..............................................  23
         1.4    Time.............................................................................................  24

SECTION 2  CREDIT FACILITY.......................................................................................  24
         2.1    Term Loans.......................................................................................  24
         2.2    Continuations and Conversions....................................................................  26
         2.3    Minimum Amounts..................................................................................  27

SECTION 3  GENERAL PROVISIONS APPLICABLE TO LOANS................................................................  27
         3.1    Interest.........................................................................................  27
         3.2    Place and Manner of Payments.....................................................................  27
         3.3    Prepayments; Revision of Amortization Schedule...................................................  28
         3.4    Fees.............................................................................................  28
         3.5    Payment in full at Maturity or Otherwise.........................................................  29
         3.6    Computations of Interest and Fees................................................................  29
         3.7    Pro Rata Treatment...............................................................................  30
         3.8    Sharing of Payments..............................................................................  30
         3.9    Capital Adequacy/Regulation D....................................................................  31
         3.10   Inability To Determine Interest Rate.............................................................  31
         3.11   Illegality.......................................................................................  32
         3.12   Requirements of Law..............................................................................  32
         3.13   Taxes............................................................................................  33
         3.14   Compensation.....................................................................................  36
         3.15   Determination and Survival of Provisions.........................................................  36
         3.16   Notification by Lenders..........................................................................  36
         3.17   Mitigation; Mandatory Assignment.................................................................  37

SECTION 4  GUARANTY..............................................................................................  37
         4.1    Guaranty of Payment..............................................................................  37
         4.2    Obligations Unconditional........................................................................  37
         4.3    Modifications....................................................................................  38
         4.4    Waiver of Rights.................................................................................  39
         4.5    Reinstatement....................................................................................  39
         4.6    Remedies.........................................................................................  39
         4.7    Limitation of Guaranty...........................................................................  40
         4.8    Rights of Contribution...........................................................................  40
         4.9    Release of Guarantors............................................................................  40

SECTION 5  CONDITIONS PRECEDENT..................................................................................  40
         5.1    Closing Conditions...............................................................................  40
</TABLE>


                                       i
<PAGE>
<TABLE>
<S>                                                                                                                <C>
         5.2    Conditions to Initial Funding of the Term Loans..................................................  40
         5.3    Conditions to All Extensions of Credit...........................................................  43

SECTION 6  REPRESENTATIONS AND WARRANTIES........................................................................  43
         6.1    Organization and Good Standing...................................................................  43
         6.2    Due Authorization................................................................................  44
         6.3    Enforceable Obligations..........................................................................  44
         6.4    No Conflicts.....................................................................................  44
         6.5    Consents.........................................................................................  44
         6.6    Financial Condition..............................................................................  45
         6.7    No Material Change...............................................................................  45
         6.8    Disclosure.......................................................................................  45
         6.9    No Default.......................................................................................  45
         6.10   Litigation.......................................................................................  45
         6.11   Taxes............................................................................................  46
         6.12   Compliance with Law..............................................................................  46
         6.13   Licensing and Accreditation......................................................................  46
         6.14   Title to Properties, Liens.......................................................................  47
         6.15   Insurance........................................................................................  47
         6.16   Use of Proceeds..................................................................................  47
         6.17   Government Regulation............................................................................  47
         6.18   ERISA............................................................................................  47
         6.19   Environmental Matters............................................................................  48
         6.20   Intellectual Property............................................................................  50
         6.21   Subsidiaries.....................................................................................  50
         6.22   Solvency.........................................................................................  50

SECTION 7  AFFIRMATIVE COVENANTS.................................................................................  50
         7.1    Information Covenants............................................................................  50
         7.2    Financial Covenants..............................................................................  53
         7.3    Preservation of Existence and Franchises.........................................................  54
         7.4    Books and Records................................................................................  54
         7.5    Compliance with Law..............................................................................  54
         7.6    Payment of Taxes and Other Indebtedness..........................................................  55
         7.7    Insurance........................................................................................  55
         7.8    Maintenance of Property..........................................................................  55
         7.9    Performance of Obligations.......................................................................  55
         7.10   Use of Proceeds..................................................................................  55
         7.11   Audits/Inspections...............................................................................  56
         7.12   Additional Credit Parties........................................................................  56
         7.13   Credit Party Revenues............................................................................  57
         7.14   Compliance Program...............................................................................  57
         7.15   Unilab Acquisition...............................................................................  57

SECTION 8  NEGATIVE COVENANTS....................................................................................  57
         8.1    Indebtedness.....................................................................................  57
         8.2    Liens............................................................................................  58
</TABLE>


                                       ii
<PAGE>
<TABLE>
<S>                                                                                                                <C>
         8.3    Nature of Business...............................................................................  58
         8.4    Consolidation and Merger.........................................................................  59
         8.5    Sale or Lease of Assets..........................................................................  59
         8.6    Investments......................................................................................  60
         8.7    Transactions with Affiliates.....................................................................  60
         8.8    Fiscal Year; Accounting; Organizational Documents................................................  60
         8.9    Stock Repurchases................................................................................  60
         8.10   Sale/Leasebacks..................................................................................  61

SECTION 9  EVENTS OF DEFAULT.....................................................................................  62
         9.1    Events of Default................................................................................  62
         9.2    Acceleration; Remedies...........................................................................  64
         9.3    Allocation of Payments After Event of Default....................................................  65

SECTION 10  AGENCY PROVISIONS....................................................................................  66
         10.1   Appointment......................................................................................  66
         10.2   Delegation of Duties.............................................................................  67
         10.3   Exculpatory Provisions...........................................................................  67
         10.4   Reliance on Communications.......................................................................  67
         10.5   Notice of Default................................................................................  68
         10.6   Non-Reliance on Administrative Agent and Other Lenders...........................................  68
         10.7   Indemnification..................................................................................  69
         10.8   Administrative Agent in Its Individual Capacity..................................................  69
         10.9   Successor Agent..................................................................................  70

SECTION 11  MISCELLANEOUS........................................................................................  70
         11.1   Notices..........................................................................................  70
         11.2   Right of Set-Off.................................................................................  70
         11.3   Benefit of Agreement.............................................................................  71
         11.4   No Waiver; Remedies Cumulative...................................................................  74
         11.5   Payment of Expenses; Indemnification.............................................................  75
         11.6   Amendments, Waivers and Consents.................................................................  75
         11.7   Counterparts/Telecopy............................................................................  76
         11.8   Headings.........................................................................................  76
         11.9   Defaulting Lender................................................................................  76
         11.10  Survival of Indemnification......................................................................  77
         11.11  Governing Law; Venue; Jurisdiction...............................................................  77
         11.12  Waiver of Jury Trial; Waiver of Consequential Damages............................................  77
         11.13  Severability.....................................................................................  78
         11.14  Further Assurances...............................................................................  78
         11.15  Confidentiality..................................................................................  78
         11.16  Entirety.........................................................................................  78
         11.17  Binding Effect; Continuing Agreement.............................................................  78
</TABLE>


                                      iii
<PAGE>
<TABLE>
<CAPTION>
SCHEDULES
---------
<S>                        <C>
Schedule 1.1(a)            Commitment Percentages/Lending Offices
Schedule 6.10              Litigation
Schedule 6.21              Subsidiaries
Schedule 8.1               Indebtedness
Schedule 8.2               Liens
Schedule 8.6               Investments
Schedule 8.7               Affiliate Transactions
Schedule 11.1              Notices
</TABLE>


<TABLE>
<CAPTION>
EXHIBITS
--------
<S>                        <C>
Exhibit 2.1(b)             Form of Notice of Borrowing
Exhibit 2.1(f)             Form of Term Note
Exhibit 2.2                Form of Notice of Continuation/Conversion
Exhibit 7.1(c)             Form of Officer's Certificate
Exhibit 7.12               Form of Joinder Agreement
Exhibit 11.3(b)            Form of Assignment Agreement
</TABLE>


                                       iv
<PAGE>
                           TERM LOAN CREDIT AGREEMENT


         THIS Term Loan Credit Agreement (this "Credit Agreement"), is entered
into as of June 21, 2002 among QUEST DIAGNOSTICS INCORPORATED, a Delaware
corporation (the "Borrower"), certain of the Subsidiaries of the Borrower
(individually a "Guarantor" and collectively the "Guarantors"), the Lenders (as
defined herein), and BANK OF AMERICA, N.A., as Administrative Agent for the
Lenders.

                                    RECITALS

         WHEREAS, the Borrower and the Guarantors have requested the Lenders to
provide a term loan credit facility to the Borrower in an aggregate principal
amount of up to $450,000,000; and

         WHEREAS, the Lenders party hereto have agreed to make the requested
term loan credit facility available to the Borrower on the terms and conditions
hereinafter set forth.

         NOW, THEREFORE, IN CONSIDERATION of the premises and other good and
valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, the parties hereto agree as follows:

                                    SECTION 1

                        DEFINITIONS AND ACCOUNTING TERMS

         1.1 DEFINITIONS.

         As used herein, the following terms shall have the meanings herein
specified unless the context otherwise requires. Defined terms herein shall
include in the singular number the plural and in the plural the singular:

         "Acquisition" means the acquisition by any Person of (a) more than 50%
of the Capital Stock of another Person, (b) all or substantially all of the
assets of another Person or (c) all or substantially all of a line of business
of another Person, in each case whether or not involving a merger or
consolidation with such other Person.

         "Additional Credit Party" means each Person that becomes a Guarantor
after the Closing Date, as provided in Section 7.12 or otherwise.

         "Adjusted Eurodollar Rate" means the Eurodollar Rate plus the
Applicable Percentage.

         "Administrative Agent" means Bank of America, N.A. (or any successor
thereto) or any successor administrative agent appointed pursuant to Section
10.9.
<PAGE>
         "Administrative Fees" has the meaning set forth in Section 3.4.

         "Affiliate" means, with respect to any Person, any other Person
directly or indirectly controlling (including but not limited to all directors
and officers of such Person), controlled by or under direct or indirect common
control with such Person. A Person shall be deemed to control a corporation if
such Person possesses, directly or indirectly, the power (a) to vote 10% or more
of the securities having ordinary voting power for the election of directors of
such corporation or (b) to direct or cause direction of the management and
policies of such corporation, whether through the ownership of voting
securities, by contract or otherwise.

         "Agency Services Address" means Bank of America, N.A., NC1-001-15-04,
101 North Tryon Street, Charlotte, North Carolina 28255, Attn: Agency Services,
Attn: Credit Services, or such other address as may be identified by written
notice from the Administrative Agent to the Borrower.

         "Agent-Related Person" means the Administrative Agent (including any
successor administrative agent), together with its Affiliates (including, in the
case of Bank of America in its capacity as the Administrative Agent, BAS), and
their respective officers, directors, employees, agents, counsel and
attorneys-in-fact.

         "Agents" means Bank of America N.A., in its capacity as Administrative
Agent, and Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith
Incorporated, in its capacity as Syndication Agent.

         "AML Acquisition" means the Borrower's acquisition of American Medical
Laboratories, Inc. on April 1, 2002 as described in the Borrower's Form 8-K
dated April 1, 2002 filed with the United States Securities and Exchange
Commission.

         "Applicable Percentage" means the appropriate applicable percentages
corresponding to the Debt Rating of the Borrower in effect from time to time as
described below:

<TABLE>
<CAPTION>
                                                                     Applicable
                                                                   Percentage for
Pricing Level                    Debt Rating                      Eurodollar Loans
-------------                    -----------                      ----------------
<S>             <C>                                               <C>
     I          greater than or equal to BBB+ from S&P/                   .875%
                greater than or equal to Baa1 from Moody's
    II          greater than or equal to BBB but < BBB+ from            1.1875%
                S&P/
                greater than or equal to Baa2 but <Baa1 from
                Moody's
   III          greater than or equal to BBB- but <BBB from S&P/        1.3125%
                greater than or equal to Baa3 but <Baa2 from
                Moody's
    IV          greater than or equal to BB+ but < BBB- from            1.4375%
                S&P/
                greater than or equal to Ba1 but <Baa3 from
                Moody's
     V          <BB+ or unrated by S&P/                                 1.6875%
                <Ba1 or unrated by Moody's
</TABLE>

The Applicable Percentage for Eurodollar Loans shall, in each case, be
determined and adjusted on the date (each a "Calculation Date") one Business Day
after the date on which the Borrower's Debt Rating is upgraded or downgraded in
a manner which requires a


                                       2
<PAGE>
change in the then applicable Pricing Level set forth above. If at any time
there is a split in the Borrower's Debt Ratings between S&P and Moody's, the
Applicable Percentages shall be determined by the higher of the two Debt Ratings
(i.e. the lower pricing); provided that if the two Debt Ratings are more than
one level apart, the Applicable Percentage shall be based on the Debt Rating
which is one level higher than the lower rating. Each Applicable Percentage
shall be effective from one Calculation Date until the next Calculation Date.
Any adjustment in the Applicable Percentage shall be applicable to all existing
Eurodollar Loans as well as any new Eurodollar Loans made.

         "Approved Fund" means any Fund that is administered or managed by (a) a
Lender, (b) an Affiliate of a Lender or (c) an entity or an Affiliate of an
entity that administers or manages a Lender.

         "Attorney Costs" means all reasonable fees and disbursements of any law
firm or other external counsel and the reasonable allocated cost of internal
legal services and all disbursements of internal counsel.

         "Attributable Debt" means, with respect to a Sale and Leaseback
Transaction, an amount equal to the lesser of: (a) the fair market value of the
Principal Property (as determined in good faith by the Borrower's board of
directors); and (b) the present value of the total net amount of rent payments
to be made under the lease during its remaining term, discounted at the rate of
interest set forth or implicit in the terms of the lease, compounded
semi-annually.

         "Authorized Officer" means any of the chief executive officer,
president, chief financial officer, corporate controller, treasurer or assistant
treasurer of the Borrower.

         "Bank of America" means Bank of America, N.A. or any successor thereto.

         "Bankruptcy Code" means the Bankruptcy Code in Title 11 of the United
States Code, as amended, modified, succeeded or replaced from time to time.

         "BAS" means Banc of America Securities LLC.

         "Base Rate" means, for any day, the rate per annum equal to the greater
of (a) the Federal Funds Rate in effect on such day plus 1/2 of 1% or (b) the
Prime Rate in effect on such day. If for any reason the Administrative Agent
shall have determined (which determination shall be conclusive absent manifest
error) that it is unable after due inquiry to ascertain the Federal Funds Rate
for any reason, including the inability or failure of the Administrative Agent
to obtain sufficient quotations in accordance with the terms hereof, the Base
Rate shall be determined without regard to clause (a) of the first sentence of
this definition until the circumstances giving rise to such inability no longer
exist. Any change in the Base Rate due to a change in the Prime Rate or the
Federal Funds Rate shall be effective at the opening of business on the day
specified in the public announcement of such change.


                                       3
<PAGE>
         "Base Rate Loan" means any Term Loan bearing interest at a rate
determined by reference to the Base Rate.

         "Borrower" means Quest Diagnostics Incorporated, a Delaware
corporation, together with any successors and permitted assigns.

         "Business Day" means any day other than a Saturday, a Sunday, a legal
holiday or a day on which banking institutions are authorized or required by law
or other governmental action to close in New York, New York or Charlotte, North
Carolina; provided that in the case of Eurodollar Loans, such day is also a day
on which dealings between banks are carried on in U.S. dollar deposits in the
London interbank market.

         "Calculation Date" has the meaning set forth in the definition of
Applicable Percentage.

         "CAP" means the College of American Pathologists.

         "Capital Expenditures" means all expenditures of the Borrower and its
Subsidiaries on a consolidated basis which, in accordance with GAAP, would be
classified as capital expenditures, including, without limitation, Capital
Leases which would be so classified in accordance with GAAP.

         "Capital Lease" means, as applied to any Person, any lease of any
Property (whether real, personal or mixed) by that Person as lessee which, in
accordance with GAAP, is or should be accounted for as a capital lease on the
balance sheet of that Person and the amount of such obligation shall be the
capitalized amount thereof determined in accordance with GAAP.

         "Capital Stock" means (a) in the case of a corporation, all classes of
capital stock of such corporation, (b) in the case of a partnership, partnership
interests (whether general or limited), (c) in the case of a limited liability
company, membership interests and (d) any other interest or participation that
confers on a Person the right to receive a share of the profits and losses of,
or distributions of assets of, the issuing Person.

         "Cash Equivalents" means (a) securities issued or directly and fully
guaranteed or insured by the United States of America or any agency or
instrumentality thereof (provided that the full faith and credit of the United
States of America is pledged in support thereof) having maturities of not more
than eighteen months from the date of acquisition, (b) Dollar denominated time
and demand deposits, certificates of deposit and banker's acceptances of (i) any
Lender, (ii) any domestic commercial bank having capital and surplus in excess
of $500,000,000 or (iii) any bank whose short-term commercial paper rating from
S&P is at least A-1 or the equivalent thereof or from Moody's is at least P-1 or
the equivalent thereof (any such bank being an "Approved Bank"), in each case
with maturities of not more than 270 days from the date of acquisition, (c)
commercial paper and variable or fixed rate notes issued by any Approved Bank
(or by the parent company thereof) or any variable rate notes issued by, or
guaranteed by, any domestic corporation rated A-1 (or the equivalent thereof)


                                       4
<PAGE>
or better by S&P or P-1 (or the equivalent thereof) or better by Moody's and
maturing within six months of the date of acquisition, (d) repurchase agreements
with a bank or trust company (including any of the Lenders) or recognized
securities dealer having capital and surplus in excess of $500,000,000 for
direct obligations issued by or fully guaranteed by the United States of America
in which the Borrower shall have a perfected first priority security interest
(subject to no other Liens) and having, on the date of purchase thereof, a fair
market value of at least 100% of the amount of the repurchase obligations, (e)
Investments in tax-exempt municipal bonds rated A (or the equivalent thereof) or
better by S&P or MIG2 (or the equivalent thereof) or better by Moody's and (f)
Investments, classified in accordance with GAAP as current assets, in money
market investment programs registered under the Investment Company Act of 1940,
as amended, which are administered by reputable financial institutions having
capital of at least $500,000,000 and the portfolios of which are limited to
Investments of the character described in the foregoing subdivisions (a) through
(e).

         "Cash Interest Expenses" means all Interest Expense actually paid in
cash by the Borrower and its Subsidiaries.

         "Cash Taxes" means the total amount of federal, state, foreign or other
income or franchise taxes, paid in cash, of the Borrower and its Subsidiaries on
a consolidated basis.

         "CHAMPUS" means the United States Department of Defense Civilian Health
and Medical Program of the United States or any successor thereto including,
without limitation, TRICARE.

         "Change of Control" means either of the following events:

                  (a) any "person" or "group" (within the meaning of Section
         13(d) or 14(d) of the Exchange Act) has become, directly or indirectly,
         the "beneficial owner" (as defined in Rules 13d-3 and 13d-5 under the
         Exchange Act), by way of merger, consolidation or otherwise of 35% or
         more of the Voting Stock of the Borrower on a fully-diluted basis,
         after giving effect to the conversion and exercise of all outstanding
         warrants, options and other securities of the Borrower convertible into
         or exercisable for Voting Stock of the Borrower (whether or not such
         securities are then currently convertible or exercisable); or

                  (b) during any period of twelve calendar months, individuals
         who at the beginning of such period constituted the board of directors
         of the Borrower together with any new members of such board of
         directors whose elections by such board or board of directors or whose
         nomination for election by the stockholders of the Borrower was
         approved by a vote of a majority of the members of such board of
         directors then still in office who either were directors at the
         beginning of such period or whose election or nomination for election
         was previously so approved cease for any reason to constitute a
         majority of the directors of the Borrower then in office.


                                       5
<PAGE>
         "CLIA" means the Clinical Laboratory Improvement Act as set forth at 42
U.S.C. 263a and the regulations promulgated thereunder, as amended.

         "Closing Date" means the date hereof.

         "Co-Documentation Agents" means Wachovia Bank, National Association,
Deutsche Bank Securities Inc. and The Bank of New York in their capacity as
co-documentation agents hereunder.

         "Code" means the Internal Revenue Code of 1986 and the rules and
regulations promulgated thereunder, as amended, modified, succeeded or replaced
from time to time.

         "Commitments" means the commitment of each Lender with respect to the
Term Loan Committed Amount.

         "Convertible Notes" means those certain 1 -3/4% contingent convertible
debentures due November 30, 2021 issued by the Borrower in an aggregate
principal amount of $250,000,000.

         "Credit Documents" means this Credit Agreement, the Notes, any Joinder
Agreement and any Notice of Borrowing.

         "Credit Exposure" has the meaning set forth in the definition of
Required Lenders in this Section 1.1.

         "Credit Parties" means the Borrower and the Guarantors and "Credit
Party" means any one of them.

         "Credit Party Obligations" means, without duplication, all of the
obligations of the Credit Parties to the Lenders and the Administrative Agent,
whenever arising, under this Credit Agreement, the Notes, or any of the other
Credit Documents.

         "Debt Rating" means the long-term senior unsecured, non-credit enhanced
debt rating of the Borrower from S&P and Moody's.

         "Default" means any event, act or condition which with notice or lapse
of time, or both, would constitute an Event of Default.

         "Defaulting Lender" means, at any time, any Lender that, (a) has failed
to make a Loan or purchase a Participation Interest required pursuant to the
terms of this Credit Agreement (but only for so long as such Loan is not made or
such Participation Interest is not purchased), (b) has failed to pay to the
Administrative Agent or any Lender an amount owed by such Lender pursuant to the
terms of this Credit Agreement (but only for so long as such amount has not been
repaid) or (c) has been deemed insolvent or has become subject to a bankruptcy
or insolvency proceeding or to a receiver, trustee or similar official.


                                       6
<PAGE>
         "Dividends" means any payment of dividends or any other distribution
upon any shares of any class of Capital Stock of the Borrower.

         "Dollars" and "$" means dollars in lawful currency of the United States
of America.

         "Domestic Subsidiary" means each direct and indirect Subsidiary of the
Borrower that is domiciled or organized under the laws of any State of the
United States or the District of Columbia.

         "EBITDA" means, for any period, with respect to the Borrower and its
Subsidiaries on a consolidated basis, (a) Net Income for such period (excluding
the effect of any extraordinary or other non-recurring gains and losses
(including any gain or loss from the sale of Property)) plus (b) an amount
which, in the determination of Net Income for such period, has been deducted for
(i) Interest Expense for such period, (ii) total Federal, state, foreign or
other income or franchise taxes for such period, (iii) all depreciation and
amortization for such period, (iv) other items of expense during such period
that do not involve a cash payment at any time (other than the provision for bad
debt in connection with uncollectible accounts receivable), (v) cash charges
during such period for which the Borrower and its Subsidiaries are reimbursed by
a third party during such period and (vi) special or restructuring items during
any such period included in Net Income that do not involve a cash payment during
such period (collectively, "Non-Cash Items") minus (c) any actual cash payments
during the applicable period related to Non-Cash Items expensed or reserved
under clause (vi) above during an applicable period beginning after March 31,
2001 plus (d) Tender Costs during such period.

         "Eligible Assets" means (a) MedPlus and its Subsidiaries and (b) any
assets or any business (or any substantial part thereof) used or useful in the
same or a similar line of business as the Borrower and its Subsidiaries are
engaged on the Closing Date or other healthcare-related businesses.

         "Eligible Assignee" means (a) a Lender; (b) an Affiliate of a Lender;
(c) an Approved Fund; and (d) any other Person approved by the Administrative
Agent and the Borrower (such approval not to be unreasonably withheld or
delayed); provided that (i) the Borrower's consent is not required during the
existence and continuation of a Default or an Event of Default, (ii) approval by
the Borrower shall be deemed given if no objection is received by the assigning
Lender and the Administrative Agent from the Borrower within five Business Days
after notice of such proposed assignment has been delivered to the Borrower;
(iii) neither the Borrower nor an Affiliate of the Borrower shall qualify as an
Eligible Assignee; and (iv) no competitor of the Borrower shall qualify as an
Eligible Assignee.

         "Environmental Laws" means any current or future legally enforceable
requirement of any Governmental Authority pertaining to (a) the protection of
the indoor or outdoor environment, (b) the conservation, management, or use of
natural resources and wildlife, (c) the protection or use of surface water and
groundwater or (d) the management, manufacture, possession, presence, use,
generation, transportation, treatment, storage, disposal, release,


                                       7
<PAGE>
threatened release, abatement, removal, remediation or handling of, or exposure
to, any hazardous or toxic substance or material or (e) pollution (including any
release to land surface water and groundwater) and includes, without limitation,
the Comprehensive Environmental Response, Compensation, and Liability Act of
1980, as amended by the Superfund Amendments and Reauthorization Act of 1986, 42
USC 9601 et seq., Solid Waste Disposal Act, as amended by the Resource
Conservation and Recovery Act of 1976 and Hazardous and Solid Waste Amendments
of 1984, 42 USC 6901 et seq., Federal Water Pollution Control Act, as amended by
the Clean Water Act of 1977, 33 USC 1251 et seq., Clean Air Act of 1966, as
amended, 42 USC 7401 et seq., Toxic Substances Control Act of 1976, 15 USC 2601
et seq., Hazardous Materials Transportation Act, 49 USC App. 1801 et seq.,
Occupational Safety and Health Act of 1970, as amended, 29 USC 651 et seq., Oil
Pollution Act of 1990, 33 USC 2701 et seq., Emergency Planning and Community
Right-to-Know Act of 1986, 42 USC 11001 et seq., National Environmental Policy
Act of 1969, 42 USC 4321 et seq., Safe Drinking Water Act of 1974, as amended,
42 USC 300(f) et seq., any analogous implementing or successor law, and any
amendment, rule, regulation, order, or directive issued thereunder.

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended, and any successor statute thereto, as interpreted by the rules and
regulations thereunder, all as the same may be in effect from time to time.
References to sections of ERISA shall be construed also to refer to any
successor sections.

         "ERISA Affiliate" means an entity, whether or not incorporated, which
is treated as a single employer with the Borrower or any Subsidiary of the
Borrower under Sections 414(b) or (c) of the Code and solely for purposes of
Section 412 of the Code under Section 414(m) of the Code.

         "ERISA Event" means (a) with respect to any Single Employer or Multiple
Employer Plan, the occurrence of a Reportable Event or the substantial cessation
of operations (within the meaning of Section 4062(e) of ERISA); (b) the
withdrawal of the Borrower, any Subsidiary of the Borrower or any ERISA
Affiliate from a Multiple Employer Plan during a plan year in which it was a
substantial employer (as such term is defined in Section 4001(a)(2) of ERISA),
or the termination of a Multiple Employer Plan; (c) the distribution of a notice
of intent to terminate or the actual termination of a Plan pursuant to Section
4041(a)(2) or 4041A of ERISA; (d) the institution of proceedings to terminate or
the actual termination of any Plan by the PBGC under Section 4042 of ERISA; (e)
any event or condition which might constitute grounds under Section 4042 of
ERISA for the termination of, or the appointment of a trustee to administer, any
Plan; (f) the complete or partial withdrawal of the Borrower, any Subsidiary of
the Borrower or any ERISA Affiliate from a Multiemployer Plan or notification
that a Multiemployer Plan is in reorganization; (g) the conditions for
imposition of a lien under Section 302(f) of ERISA exist with respect to any
Plan; or (h) the adoption of an amendment to any Plan requiring the provision of
security to such Plan pursuant to Section 307 of ERISA.

         "Eurodollar Loan" means a Loan bearing interest based at a rate
determined by reference to the Eurodollar Rate.


                                       8
<PAGE>
         "Eurodollar Rate" means, for the Interest Period for each Eurodollar
Loan comprising part of the same borrowing (including conversions, extensions
and renewals), a per annum interest rate equal to the London Interbank Offered
Rate.

         "Eurodollar Reserve Percentage" means, with respect to each Lender, the
percentage (expressed as a decimal) applicable to such Lender which is in effect
from time to time under Regulation D as the reserve requirement (including,
without limitation, any basic, supplemental, emergency, special, or marginal
reserves) applicable with respect to its Eurocurrency liabilities, as that term
is defined in Regulation D (or against any other category of liabilities that
includes deposits by reference to which the interest rate of Eurodollar Loans is
determined). Eurodollar Loans made by a Lender shall be deemed to constitute
Eurocurrency liabilities and as such shall be deemed subject to reserve
requirements, if applicable, without benefits of credits for proration,
exceptions or offsets that may be available from time to time to such Lender.

         "Event of Default" means any of the events or circumstances specified
in Section 9.1.

         "Exchange Act" means the Securities Exchange Act of 1934, as amended,
and the rules and regulations promulgated thereunder, as amended, modified,
succeeded or replaced from time to time.

         "Extension of Credit" means, as to any Lender, the making of a Loan by
such Lender (or a participation therein by a Lender).

         "Federal Funds Rate" means for any day the rate per annum equal to the
weighted average of the rates on overnight Federal funds transactions with
members of the Federal Reserve System arranged by Federal funds brokers on such
day, as published by the Federal Reserve Bank of New York on the Business Day
next succeeding such day; provided that (a) if such day is not a Business Day,
the Federal Funds Rate for such day shall be such rate on such transactions on
the next preceding Business Day and (b) if no such rate is so published on such
next preceding Business Day, the Federal Funds Rate for such day shall be the
average rate quoted to the Administrative Agent on such day on such transactions
from three Federal Funds brokers of recognized standing selected by it.

         "Fee Letter" means that certain letter agreement dated as of March 27,
2002 among the Borrower, BAS, the Agents and Merrill Lynch Capital Corporation
relating to the transactions contemplated by this Credit Agreement, as amended
from time to time.

         "Fixed Charge Coverage Ratio" means, as of the end of each fiscal
quarter of the Credit Parties for the twelve month period ending on such date,
with respect to the Borrower and its Subsidiaries on a consolidated basis, the
ratio of (a) the sum of (i) EBITDA for such period minus (ii) Capital
Expenditures for such period minus (iii) Cash Taxes for such period to (b) the
sum of (i) Cash Interest Expense for such period plus (ii) Scheduled


                                       9
<PAGE>
Funded Debt Payments, after giving effect to any reductions arising from
voluntary prepayments previously made, for such period, plus (iii) cash
Dividends for such period.

         "Foreign Subsidiary" means any Subsidiary of the Borrower that is not a
Domestic Subsidiary.

         "Fund" means any Person (other than a natural person) that is (or will
be) engaged in making, purchasing, holding or otherwise investing in commercial
loans and similar extensions of credit in the ordinary course of its business.

         "Funded Debt" means, without duplication, the sum of (a) all
Indebtedness of the Borrower and its Subsidiaries for borrowed money, (b) all
purchase money Indebtedness of the Borrower and its Subsidiaries, (c) the
principal portion of all obligations of the Borrower and its Subsidiaries under
Capital Leases, (d) all drawn but unreimbursed amounts under all letters of
credit (other than letters of credit supporting trade payables in the ordinary
course of business) issued for the account of the Borrower or any of its
Subsidiaries, (e) all Funded Debt of another Person secured by a Lien on any
Property of the Borrower and its Subsidiaries whether or not such Funded Debt
has been assumed by a Borrower or any of its Subsidiaries, (f) all Funded Debt
of any partnership or unincorporated joint venture to the extent the Borrower or
one of its Subsidiaries is legally obligated with respect thereto and (g) the
amount of principal attributable under any outstanding Synthetic Lease. It is
understood and agreed that Indebtedness incurred pursuant to Hedging Agreements
is not Funded Debt.

         "Funding Date" means the date on which all of the conditions set forth
in Section 5.2 have been fulfilled (or waived in the sole discretion of the
Lenders) and on which the initial Loans have been made.

         "GAAP" means generally accepted accounting principles in the United
States applied on a consistent basis and subject to Section 1.3.

         "Governmental Authority" means any Federal, state, local, provincial or
foreign court or governmental agency, authority, instrumentality or regulatory
body.

         "Guarantor" means each of the Material Domestic Subsidiaries of the
Borrower, any other Subsidiary of the Borrower that guaranties the Senior
Unsecured Notes or the 2001 Senior Credit Agreement and each Additional Credit
Party, together with their successors and assigns.

         "Guaranty" means the guaranty of the Credit Party Obligations provided
by the Guarantors pursuant to Section 4.

         "Guaranty Obligations" means, with respect to any Person, without
duplication, any obligations (other than endorsements in the ordinary course of
business of negotiable instruments for deposit or collection) guaranteeing any
Indebtedness of any other Person in any manner, whether direct or indirect, and
including without limitation any obligation,


                                       10
<PAGE>
whether or not contingent, (a) to purchase any such Indebtedness or other
obligation or any Property constituting security therefor, (b) to advance or
provide funds or other support for the payment or purchase of such Indebtedness
or obligation or to maintain working capital, solvency or other balance sheet
condition of such other Person (including, without limitation, maintenance
agreements, comfort letters, take or pay arrangements, put agreements or similar
agreements or arrangements) for the benefit of the holder of Indebtedness of
such other Person, (c) to lease or purchase Property, securities or services
primarily for the purpose of assuring the owner of such Indebtedness or (d) to
otherwise assure or hold harmless the owner of such Indebtedness or obligation
against loss in respect thereof. The amount of any Guaranty Obligation hereunder
shall (subject to any limitations set forth therein) be deemed to be an amount
equal to the outstanding principal amount (or maximum principal amount, if
larger) of the Indebtedness in respect of which such Guaranty Obligation is
made.

         "Hazardous Materials" means any substance, material or waste defined in
or regulated under any Environmental Laws.

         "HCFA" means the United States Health Care Financing Administration and
any successor thereto.

         "Hedging Agreements" means, collectively, interest rate protection
agreements, foreign currency exchange agreements, commodity purchase or option
agreements or other interest or exchange rate or commodity price hedging
agreements, in each case, entered into or purchased by a Credit Party.

         "Indebtedness" of any Person means, without duplication, (a) all
obligations of such Person for borrowed money, (b) all obligations of such
Person evidenced by bonds, debentures, notes or similar instruments, or upon
which interest payments are customarily made, (c) all obligations of such Person
under conditional sale or other title retention agreements relating to Property
purchased by such Person to the extent of the value of such Property (other than
customary reservations or retentions of title under agreements with suppliers
entered into in the ordinary course of business), (d) all obligations, other
than intercompany items, of such Person issued or assumed as the deferred
purchase price of property or services purchased by such Person which would
appear as liabilities on a balance sheet of such Person, (e) all Indebtedness of
others secured by (or for which the holder of such Indebtedness has an existing
right, contingent or otherwise, to be secured by) any Lien on, or payable out of
the proceeds of production from, property owned or acquired by such Person,
whether or not the obligations secured thereby have been assumed, (f) all
Guaranty Obligations of such Person, (g) the principal portion of all
obligations of such Person under (i) Capital Leases and (ii) any Synthetic
Lease, (h) all obligations of such Person to repurchase any securities which
repurchase obligation is related to the issuance thereof, including, without
limitation, obligations commonly known as residual equity appreciation potential
shares, (i) all net obligations of such Person in respect of Hedging Agreements,
(j) the maximum amount of all performance and standby letters of credit issued
or bankers' acceptances facilities created for the account of such Person and,
without duplication, all drafts drawn thereunder (to the extent unreimbursed),
and (k) the aggregate


                                       11
<PAGE>
amount of uncollected accounts receivable of such Person subject at such time to
a sale of receivables (or similar transaction) regardless of whether such
transaction is effected without recourse to such Person or in a manner that
would not be reflected on the balance sheet of such Person in accordance with
GAAP. The Indebtedness of any Person shall include the Indebtedness of any
partnership or unincorporated joint venture for which such Person is legally
obligated.

         "Indemnified Liabilities" has the meaning set forth in Section 11.5.

         "Intellectual Property" has the meaning set forth in Section 6.20.

         "Interest Expense" means, for any period, with respect to the Borrower
and its Subsidiaries on a consolidated basis, all interest expense, including,
without duplication, the interest component under Capital Leases, as determined
in accordance with GAAP.

         "Interest Payment Date" means (a) as to Base Rate Loans, the last day
of each calendar quarter and the Maturity Date and (b) as to Eurodollar Loans,
the last day of each applicable Interest Period and the Maturity Date and in
addition, where the applicable Interest Period for a Eurodollar Loan is greater
than three months, then also the date three months from the beginning of the
Interest Period and each three months thereafter. If an Interest Payment Date
falls on a date which is not a Business Day, such Interest Payment Date shall be
deemed to be the next succeeding Business Day, except that in the case of
Eurodollar Loans where the next succeeding Business Day falls in the next
succeeding calendar month, then on the next preceding Business Day.

         "Interest Period" means, as to Eurodollar Loans, a period of two weeks'
or one, two, three or six months' duration, as the Borrower may elect,
commencing, in each case, on the date of the borrowing (including continuations
and conversions thereof); provided, however, (i) if any Interest Period would
end on a day which is not a Business Day, such Interest Period shall be extended
to the next succeeding Business Day (except that where the next succeeding
Business Day falls in the next succeeding calendar month, then on the next
preceding Business Day), (ii) no Interest Period shall extend beyond the
Maturity Date and (iii) where an Interest Period begins on a day for which there
is no numerically corresponding day in the calendar month in which the Interest
Period is to end, such Interest Period shall end on the last Business Day of
such calendar month.

         "Investment" in any Person means (a) the acquisition (whether for cash,
property, services, assumption of Indebtedness, securities or otherwise) of
assets, shares of Capital Stock, bonds, notes, debentures, partnership, joint
ventures or other ownership interests or other securities of such other Person
or (b) any deposit with, or advance, loan or other extension of credit to, such
Person (other than deposits or advances made in connection with the purchase of
equipment or other assets or services in the ordinary course of business) or (c)
any other capital contribution to or investment in such Person, including,
without limitation, any Guaranty Obligation (including any support for a letter
of credit issued on behalf of such Person) incurred for the benefit of such
Person.


                                       12
<PAGE>
         "Joinder Agreement" means a Joinder Agreement substantially in the form
of Exhibit 7.12.

         "Lender" means any of the Persons identified as a "Lender" on the
signature pages hereto, and any Eligible Assignee which may become a Lender by
way of assignment in accordance with the terms hereof, together with their
successors and permitted assigns.

         "Lending Office" means, as to any Lender, the office or offices of such
Lender described as such on Schedule 1.1(a), or such other office or offices as
a Lender may from time notify to the Borrower and the Administrative Agent.

         "Leverage Ratio" means, as of the last day of each fiscal quarter, the
ratio of (a)(i) Funded Debt on such date less (ii) if no Competitive Bid Loans,
Revolving Loans or Swing Line Loans (as all such terms are defined in the 2001
Senior Credit Agreement) are outstanding on such date, the amount of Available
Cash (as defined below) on such date to (b) EBITDA for the twelve month period
ending on such date. For the purposes hereof, "Available Cash" means all cash
and Cash Equivalents of the Borrower and its Subsidiaries located in the United
States and reflected in its consolidated balance sheet in excess of $40,000,000.

         "Lien" means any mortgage, pledge, hypothecation, assignment, deposit
arrangement, security interest, encumbrance, lien (statutory or otherwise),
preference, priority or charge of any kind, including, without limitation, any
agreement to give any of the foregoing, any conditional sale or other title
retention agreement, and any lease in the nature thereof (other than operating
leases).

         "Loan" or "Loans" means the Term Loans (or any portion thereof),
individually or collectively, as appropriate.

         "London Interbank Offered Rate" means, with respect to any Eurodollar
Loan for the Interest Period applicable thereto, the rate of interest per annum
appearing on Telerate Page 3750 (or any successor page) as the London interbank
offered rate for deposits in Dollars at approximately 11:00 A.M. (London time)
two Business Days prior to the first day of such Interest Period for a term
comparable to such Interest Period; provided, however, if more than one rate is
specified on Telerate Page 3750, the applicable rate shall be the arithmetic
mean of all such rates. If, for any reason, such rate is not available, the term
"London Interbank Offered Rate" shall mean, with respect to any Eurodollar Loan
for the Interest Period applicable thereto, the rate of interest per annum
appearing on Reuters Screen LIBO Page as the London interbank offered rate for
deposits in Dollars at approximately 11:00 A.M. (London time) two Business Days
prior to the first day of such Interest Period for a term comparable to such
Interest Period; provided, however, if more than one rate is specified on
Reuters Screen LIBO Page, the applicable rate shall be the arithmetic mean of
all such rates.

         "Material Adverse Effect" means a material adverse effect on (a) the
business, operations or financial condition of the Borrower and its Subsidiaries
taken as a whole, (b)


                                       13
<PAGE>
the ability of a Credit Party to perform its obligations under this Credit
Agreement or any of the other Credit Documents, or (c) the validity or
enforceability of this Credit Agreement, any of the other Credit Documents, or
the rights and remedies of the Lenders hereunder or thereunder taken as a whole.

         "Material Domestic Subsidiary" means any wholly-owned Domestic
Subsidiary of the Borrower that, directly or indirectly, (a) owns assets in
excess of $20,000,000 or (b) has annual revenues, as of the most recently ended
fiscal year of the Borrower, in excess of two percent (2%) of the total revenues
of the Borrower and its Subsidiaries on a consolidated basis; provided that
Quest Receivables shall not be deemed to be a Material Domestic Subsidiary.

         "Maturity Date" means (i) September 30, 2002 if the Unilab Acquisition
is not consummated on or prior to such date or (ii) June 21, 2007 if the Unilab
Acquisition is consummated on or prior to September 30, 2002.

         "Medicaid" shall mean that entitlement program under Title XIX of the
Social Security Act that provides federal grants to states for medical
assistance based on specific eligibility criteria.

         "Medicaid Provider Agreement" means an agreement entered into between a
state agency or other such entity administering the Medicaid program and a
health care provider or supplier under which the health care provider or
supplier agrees to provide services for Medicaid patients in accordance with the
terms of the agreement and Medicaid Regulations.

         "Medicaid Regulations" means, collectively, (a) all federal statutes
(whether set forth in Title XIX of the Social Security Act or elsewhere)
affecting the medical assistance program established by Title XIX of the Social
Security Act and any statutes succeeding thereto; (b) all applicable provisions
of all federal rules, regulations, manuals and orders of all Governmental
Authorities promulgated pursuant to or in connection with the statutes described
in clause (a) above and all federal administrative, reimbursement and other
guidelines of all Governmental Authorities having the force of law promulgated
pursuant to or in connection with the statutes described in clause (a) above;
(c) all state statutes and plans for medical assistance enacted in connection
with the statutes and provisions described in clauses (a) and (b) above; and (d)
all applicable provisions of all rules, regulations, manuals and orders of all
Governmental Authorities promulgated pursuant to or in connection with the
statutes described in clause (c) above and all state administrative,
reimbursement and other guidelines of all Governmental Authorities having the
force of law promulgated pursuant to or in connection with the statutes
described in clause (b) above, in each case as may be amended, supplemented or
otherwise modified from time to time.

         "Medical Reimbursement Programs" shall mean Medicare, Medicaid, CHAMPUS
and TRICARE programs and any other healthcare program operated by or


                                       14
<PAGE>
financed in whole or in part by any foreign, domestic, federal, state or local
government and any other non-government funded third party payor programs.

         "Medicare Provider Agreement" means an agreement entered into between
HCFA or other such entity administering the Medicare program on behalf of the
HCFA, and a health care provider or supplier under which the health care
provider or supplier agrees to provide services for Medicare patients in
accordance with the terms of the agreement and Medicare Regulations.

         "Medicare" shall mean that government-sponsored entitlement program
under Title XVIII of the Social Security Act that provides for a health
insurance system for eligible elderly and disabled individuals.

         "Medicare Regulations" shall mean, collectively, all Federal statutes
(whether set forth in Title XVIII of the Social Security Act or elsewhere)
affecting the health insurance program for the aged and disabled established by
Title XVIII of the Social Security Act and any statutes succeeding thereto;
together with all applicable provisions of all rules, regulations, manuals and
orders and administrative, reimbursement and other guidelines having the force
of law of all Governmental Authorities (including, without limitation, the
United States Department of Health and Human Services ("HHS"), HCFA, the OIG, or
any person succeeding to the functions of any of the foregoing) promulgated
pursuant to or in connection with any of the foregoing having the force of law,
as each may be amended, supplemented or otherwise modified from time to time.

         "MedPlus" means MedPlus, Inc., an Ohio corporation.

         "Moody's" means Moody's Investors Service, Inc., or any successor or
assignee of the business of such company in the business of rating securities.

         "Multiemployer Plan" means a Plan which is a multiemployer plan as
defined in Sections 3(37) or 4001(a)(3) of ERISA.

         "Multiple Employer Plan" means a Plan covered by Title IV of ERISA
(other than a Multiemployer Plan) in which the Borrower, any Subsidiary of the
Borrower or any ERISA Affiliate and at least one employer other than the
Borrower, any Subsidiary of the Borrower or any ERISA Affiliate are contributing
sponsors.

         "Net Income" means, for any period, the net income after taxes for such
period of the Borrower and its Subsidiaries on a consolidated basis, as
determined in accordance with GAAP.

         "Non-Cash Items" has the meaning set forth in the definition of EBITDA
in Section 1.1.

         "Non-Material Domestic Subsidiary" means any wholly-owned Domestic
Subsidiary that is not a Guarantor other than Quest Receivables.


                                       15
<PAGE>
         "Note" or "Notes" means the Term Notes, individually or collectively,
as appropriate.

         "Notice of Borrowing" means a request by the Borrower for a Loan, in
the form of Exhibit 2.1(b).

         "Notice of Continuation/Conversion" means a request by the Borrower to
continue an existing Eurodollar Loan to a new Interest Period or to convert a
Eurodollar Loan to a Base Rate Loan or a Base Rate Loan to a Eurodollar Loan, in
the form of Exhibit 2.2.

         "OIG" means the Office of Inspector General of the United States
Department of Health and Human Services.

         "Participation Interest" means the Extension of Credit by a Lender by
way of a purchase of a participation in any Loans as provided in Section 3.8.

         "PBGC" means the Pension Benefit Guaranty Corporation established
pursuant to Subtitle A of Title IV of ERISA and any successor thereto.

         "Permitted Acquisition" means (a) the Unilab Acquisition and (b) any
other Acquisition by the Borrower or any of its Subsidiaries; provided that (i)
substantially all of the Property acquired (or the Property of the Person
acquired) in such Acquisition constitutes Eligible Assets (or goodwill
associated therewith), (ii) in the case of an Acquisition of the Capital Stock
of another Person, the board of directors (or other comparable governing body)
of such other Person or its parent shall have duly approved such Acquisition,
(iii) the Leverage Ratio (A) as of the most recently ended fiscal quarter for
which an officer's certificate has been delivered pursuant to Section 7.1(c) is
less than 2.75 to 1.0 and (B) on a Pro Forma Basis giving effect to such
Acquisition is less than 2.75 to 1.0, (iv) if such Acquisition involves total
consideration (cash and non-cash) in excess of $100,000,000, the Borrower shall
deliver to the Administrative Agent, prior to the closing of such Acquisition, a
certificate of an Authorized Officer of the Borrower providing calculations
showing that the requirement in clause (b)(iii)(B) above is accurate, (v) on the
date of such Acquisition no Event of Default exists, (vi) after giving effect to
such Acquisition, no Default or Event of Default shall exist, (vii) if such
Acquisition involves the formation of a new Subsidiary of the Borrower, such
Subsidiary complies with Section 7.12 and (viii) such Acquisition is undertaken
in accordance with all laws, rules, regulations, orders, writs, judgments,
injunctions, decrees and awards to which any party to such Acquisition may be
subject.

         "Permitted Investments" means Investments which constitute the
following: (a) cash or Cash Equivalents, (b) trade accounts receivable created,
acquired or made in the ordinary course of business, (c) inventory, raw
materials, general intangibles and other current assets acquired in the ordinary
course of business, (d) Investments by the Borrower or one of its Subsidiaries
in each other, (e) Permitted Acquisitions, (f) advances to management personnel
and employees in the ordinary course of business, (g) Investments existing as of


                                       16
<PAGE>
the Closing Date; provided that any such Investment in excess of $2,000,000 is
set forth on Schedule 8.6, (h) Investments consisting of non-cash consideration
received in the form of securities, notes or similar obligations in connection
with any conveyance, sale, lease, assignment, transfer or other disposition of
any Property by the Borrower or one of its Subsidiaries to any Person, and which
are permitted hereunder, (i) increases in the value of Persons in the Strategic
Investment Portfolio that did not result from any incremental investment by the
Borrower or one of its Subsidiaries, (j) other Investments (in addition to those
set forth above) not to exceed, in the aggregate, during any consecutive period
during the term of this Credit Agreement that the Leverage Ratio is greater than
or equal to 2.75 to 1.0, the sum of (i) $50,000,000 plus (ii) the amount of cash
proceeds from sales of assets in the Strategic Investment Portfolio and (k) any
other Investment as long as (i) the Leverage Ratio (A) as of the end of the most
recent fiscal quarter for which an officer's certificate has been delivered
pursuant to Section 7.1(c) is less than 2.75 to 1.0 and (B) on a Pro Forma Basis
giving effect to such Investment is less than 2.75 to 1.0, (ii) if such
Investment involves total consideration (cash and non-cash) in excess of
$100,000,000, the Borrower shall deliver to the Administrative Agent, prior to
the closing of such Investment, a certificate of an Authorized Officer of the
Borrower providing calculations showing that the requirement in clause (k)(i)(B)
above is accurate, (iii) on the date of such Investment, no Event of Default
exists and (iv) after giving effect to such Investment no Default or Event of
Default shall exist.

         "Permitted Liens" means (a) Liens securing Credit Party Obligations, if
any, (b) Liens for taxes not yet due or Liens for taxes being contested in good
faith by appropriate proceedings for which adequate reserves determined in
accordance with GAAP have been established (and as to which the Property subject
to any such Lien is not yet subject to foreclosure, sale, collection, levy or
loss on account thereof), (c) Liens in respect of Property imposed by law
arising in the ordinary course of business such as materialmen's, mechanics',
warehousemen's, carrier's, landlords' and other nonconsensual statutory Liens
which are not yet due and payable or which are being contested in good faith by
appropriate proceedings for which adequate reserves determined in accordance
with GAAP have been established (and as to which the Property subject to any
such Lien is not yet subject to foreclosure, sale or loss on account thereof),
(d) Liens (other than Liens imposed under ERISA) consisting of pledges or
deposits made in the ordinary course of business to secure payment of worker's
compensation insurance, unemployment insurance, pensions or social security
programs, (e) Liens arising from good faith deposits in connection with or to
secure performance of tenders, bids, leases, government contracts, performance
and return-of-money bonds and other similar obligations incurred in the ordinary
course of business (other than obligations in respect of the payment of borrowed
money), (f) Liens arising from good faith deposits in connection with or to
secure performance of statutory obligations and surety and appeal bonds, (g)
easements, rights-of-way, restrictions (including zoning restrictions), matters
of plat, minor defects or irregularities in title and other similar charges or
encumbrances not, in any material respect, impairing the use of the encumbered
Property for its intended purposes, (h) judgment Liens that would not constitute
an Event of Default, (i) Liens in connection with Indebtedness permitted by
Sections 8.1(d), (j) Liens arising by virtue of any statutory or common law
provision relating to banker's liens, rights of setoff or similar rights as to
deposit accounts or other funds maintained with a creditor depository


                                       17
<PAGE>
institution, (k) Liens existing on the Closing Date and identified on Schedule
8.2, (l) Liens upon Property acquired (or the Property of a Subsidiary that is
acquired) after the Closing Date by the Borrower or its Subsidiaries, which
Liens either (i) existed on such Property before the time of such acquisition
and was not created in anticipation thereof or (ii) were created solely for the
purpose of securing Indebtedness representing, or incurred to finance or
refinance, the cost of such Property or improvements thereon; provided, however;
that (A) no such Lien shall extend to or cover any Property of any Credit Party
other than the Property so acquired and improvements thereon and proceeds
thereof, (B) the principal amount of Indebtedness secured by any such Lien shall
at no time exceed 100% of the fair market value of such Property at the time it
was acquired or constructed and (C) the Indebtedness secured by any such Lien is
permitted hereunder; provided that (x) no such Lien shall extend to any Property
other than the Property subject thereto on the closing date of such acquisition
and (y) the principal amount of the Indebtedness secured by such Liens shall not
be increased, (m) Liens in connection with Permitted Receivables Financing, (n)
Liens with respect to lease filings for notice purposes only, (o) Liens on
purchase money Indebtedness incurred by the Borrower in an amount not to exceed,
in the aggregate, $50,000,000 less Indebtedness incurred by Subsidiaries of the
Borrower pursuant to Section 8.1(d), (p) Liens on Property of non-wholly owned
Subsidiaries of the Borrowers incurred to finance working capital and (q)
renewals and extensions of the foregoing so long as such Lien (i) does not cover
any additional Property, (ii) does not secure additional Indebtedness and (iii)
is not otherwise prohibited by this Credit Agreement.

         "Permitted Receivables Financing" means any transaction entered into
pursuant to documentation reasonably acceptable to the Administrative Agent in
which (a) one or more Credit Parties sells, conveys or otherwise transfers to
Quest Receivables and (b) Quest Receivables sells, conveys or otherwise
transfers to any other Person or grants a security interest to any Person in,
any Receivables (whether now existing or hereafter acquired) of a Credit Party,
and any assets related thereto including all collateral securing such
Receivables, all contracts and all Guaranty Obligations or other obligations in
respect of such Receivables, all proceeds of such Receivables and all other
assets that are customarily transferred or in respect of which security
interests are customarily granted in connection with asset securitization
transactions involving Receivables.

         "Person" means any individual, partnership, joint venture, firm,
corporation, limited liability company, association, trust or other enterprise
(whether or not incorporated), or any Governmental Authority.

         "Plan" means any employee benefit plan (as defined in Section 3(3) of
ERISA) which is covered by ERISA and with respect to which the Borrower, any
Subsidiary of the Borrower or any ERISA Affiliate is (or, if such plan were
terminated at such time, would under Section 4069 of ERISA be deemed to be) an
"employer" within the meaning of Section 3(5) of ERISA.

         "Prime Rate" means the per annum rate of interest established from time
to time by the Administrative Agent at its principal office in Charlotte, North
Carolina (or such other principal office of the Administrative Agent as
communicated in writing to the Borrower


                                       18
<PAGE>
and the Lenders) as its Prime Rate. Any change in the interest rate resulting
from a change in the Prime Rate shall become effective as of 12:01 a.m. of the
Business Day on which each change in the Prime Rate is announced by the
Administrative Agent. The Prime Rate is a reference rate used by the
Administrative Agent in determining interest rates on certain loans and is not
intended to be the lowest rate of interest charged on any extension of credit to
any debtor.

         "Principal Property" means any real property and any related buildings,
fixtures or other improvements located in the United States owned by the
Borrower or its Subsidiaries (a) on or in which one of its 30 largest domestic
clinical laboratories conducts operations, as determined by net revenues for the
four most recent fiscal quarters for which financial statements have been filed
with the Securities and Exchange Commission, or (b) the net book value of which
at the time of the determination exceeds 1% of Total Assets.

         "Prior Senior Subordinated Notes" means those certain 10-3/4% senior
subordinated notes due 2006 that were issued by the Borrower and were tendered
for in connection with the closing of the 2001 Senior Credit Agreement.

         "Pro Forma Basis" means, in connection with any Permitted Acquisition,
Permitted Investment or Stock Repurchase, that such Acquisition, Investment, or
Stock Repurchase occurred as of the end of the last fiscal quarter for which the
Borrower has delivered an officer's certificate pursuant to Section 7.1(c).

         "Property" means any right, title or interest in or to any property or
asset of any kind whatsoever, whether real, personal or mixed and whether
tangible or intangible.

         "Quest Receivables" means Quest Diagnostics Receivables Incorporated, a
Delaware corporation, a wholly-owned, bankruptcy-remote, special purpose
Subsidiary of the Borrower.

         "Real Properties" has the meaning given thereto in Section 6.19.

         "Receivable" means the indebtedness and payment obligations of any
Person to any Credit Party or acquired by any Credit Party (including
obligations constituting an account or general intangible or evidenced by a
note, instrument, contract, security agreement, chattel paper or other evidence
of indebtedness or security) arising from a sale of merchandise or the provision
of services in the ordinary course of business by such Credit Party or the
Person from which such indebtedness and payment obligation were acquired by any
Credit Party, including (a) any right to payment for goods sold or for services
rendered and (b) the right to payment of any interest, sales taxes, finance
charges, returned check or late charges and other obligations of such Person
with respect thereto.

         "Regulation A, D, T, U or X" means Regulation A, D, T, U or X,
respectively, of the Board of Governors of the Federal Reserve System as from
time to time in effect and any successor to all or a portion thereof.


                                       19
<PAGE>
         "Required Lenders" means Lenders whose aggregate Credit Exposure (as
hereinafter defined) constitutes more than 50% of the Credit Exposure of all
Lenders at such time; provided, however, that if any Lender shall be a
Defaulting Lender at such time then the aggregate principal amount of Credit
Exposure of such Lender at such time shall be excluded from the determination of
Required Lenders. For purposes hereof, the term "Credit Exposure" as applied to
each Lender shall mean (a) at any time prior to the termination of the
Commitments, the Term Loan Commitment Percentage of such Lender multiplied by
the Term Loan Committed Amount and (b) at any time after the termination of the
Commitments, the principal balance of the outstanding Loans of such Lender.

         "Requirement of Law" means, as to any Person, the articles or
certificate of incorporation and by-laws or other organizational or governing
documents of such Person, and any law, treaty, rule or regulation or final,
non-appealable determination of an arbitrator or a court or other Governmental
Authority, in each case applicable to or binding upon such Person or to which
any of its material Property is subject.

         "Reportable Event" means any of the events set forth in Section 4043(c)
of ERISA, other than those events as to which the notice requirement has been
waived by regulation or by the PBGC.

         "Sale and Leaseback Transaction" means any arrangement with any Person
providing for the leasing by the Borrower or one of its Subsidiaries of any
Principal Property that has been or is to be sold or transferred by the Borrower
or any Guarantor to such Person, as the case may be.

         "S&P" means Standard & Poor's Ratings Services, a division of The
McGraw-Hill Companies, Inc. or any successor or assignee of the business of such
division in the business of rating securities.

         "SBCL Acquisition Agreement" means the Stock and Asset Purchase
Agreement, dated as of February 9, 1999, among the Borrower, SmithKline Beecham
plc and SmithKline Beecham Corporation, as amended.

         "Scheduled Funded Debt Payments" means, for any period, with respect to
the Borrower and its Subsidiaries on a consolidated basis, the sum of all
scheduled payments of principal on Funded Debt (including the implied principal
component of payments due on Capital Leases and Synthetic Leases). It is
understood and agreed that any amortization payments made in connection with a
Permitted Receivables Financing are not Scheduled Funded Debt Payments;
provided, however, should such Indebtedness pursuant to a Permitted Receivables
Financing be required to be repaid due to the termination (whether at its stated
maturity or otherwise) of such Permitted Receivables Financing and should no
replacement facility be in effect on such termination date, the repayment of
such Indebtedness shall constitute a Scheduled Funded Debt Payment.


                                       20
<PAGE>
         "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder, as amended, modified, succeeded or
replaced from time to time.

         "Senior Unsecured Notes" means those certain senior unsecured notes
issued by the Borrower on June 27, 2001.

         "Single Employer Plan" means any Plan which is covered by Title IV of
ERISA, but which is not a Multiemployer Plan or a Multiple Employer Plan.

         "Social Security Act" means the Social Security Act as set forth in
Title 42 of the United States Code, as amended, and any successor statute
thereto, as interpreted by the rules and regulations issued thereunder, in each
case as in effect from time to time. References to sections of the Social
Security Act shall be construed also to refer to any successor sections.

         "Solvent" means, with respect to any Person as of a particular date,
that on such date (a) such Person is able to pay its debts and other
liabilities, contingent obligations and other commitments as they mature in the
normal course of business, (b) such Person does not intend to, and does not
believe that it will, incur debts or liabilities beyond such Person's ability to
pay as such debts and liabilities mature in their ordinary course, (c) such
Person is not engaged in a business or a transaction, and is not about to engage
in a business or a transaction, for which such Person's assets would constitute
unreasonably small capital after giving due consideration to the prevailing
practice in the industry in which such Person is engaged or is to engage, (d)
the fair value of the assets of such Person is greater than the total amount of
liabilities, including, without limitation, contingent liabilities, of such
Person and (e) the present fair saleable value of the assets of such Person is
not less than the amount that will be required to pay the probable liability of
such Person on its debts as they become absolute and matured. In computing the
amount of contingent liabilities at any time, it is intended that such
liabilities will be computed at the amount which, in light of all the facts and
circumstances existing at such time, represents the amount that can reasonably
be expected to become an actual or matured liability reduced by the amount of
any contribution or indemnity that can reasonably be expected to be received.

         "Stock Repurchase" has the meaning set forth in Section 8.9.

         "Strategic Investment Portfolio" means all Investments in Persons in
which the Borrower and its Subsidiaries own less than 50% of the Voting Stock of
such Person.

         "Subsidiary" means, as to any Person, (a) any corporation more than 50%
of whose stock of any class or classes having by the terms thereof ordinary
voting power to elect a majority of the directors of such corporation
(irrespective of whether or not at the time, any class or classes of such
corporation shall have or might have voting power by reason of the happening of
any contingency) is at the time owned by such Person directly or indirectly
through Subsidiaries, and (b) any partnership, association, joint venture or
other entity in


                                       21
<PAGE>
which such person directly or indirectly through Subsidiaries has more than a
50% equity interest at any time.

         "Synthetic Lease" means any synthetic lease, tax retention operating
lease, off-balance sheet loan or similar off-balance sheet financing product
where such transaction is considered borrowed money indebtedness for tax
purposes but is classified as an operating lease in accordance with GAAP.

         "Tender Costs" means the costs incurred by the Borrower in connection
with the tender for the Prior Senior Subordinated Notes and the termination of
the interest rate swap contracts existing prior to June 27, 2001 in an aggregate
amount not to exceed $20,000,000.

         "Term Loan Commitment Percentage" means, for each Lender, the
percentage identified as its Term Loan Commitment Percentage on Schedule 1.1(a),
as such percentage may be modified in connection with any assignment made in
accordance with the provisions of Section 11.3.

         "Term Loan Committed Amount" means FOUR HUNDRED FIFTY MILLION DOLLARS
($450,000,000).

         "Term Loans" means the Term Loans made to the Borrower pursuant to
Section 2.1.

         "Term Notes" means the promissory notes of the Borrower in favor of
each of the Lenders evidencing the Term Loans provided pursuant to Section 2.1,
individually or collectively, as appropriate, as such promissory notes may be
amended, modified, supplemented, extended, renewed or replaced from time to time
and as evidenced in the form of Exhibit 2.1(f).

         "Total Assets" means all items that in accordance with GAAP would be
classified as assets of the Borrower and its Subsidiaries on a consolidated
basis.

         "TRICARE" means the United States Department of Defense health care
program for service families including, but not limited to, TRICARE Prime,
TRICARE Extra and TRICARE Standard, and any successor to or predecessor thereof
(including, without limitation, CHAMPUS).

         "2001 Senior Credit Agreement" means that certain Credit Agreement,
dated as of June 27, 2001, among the Borrower, as borrower, the guarantors party
thereto, the lenders signatories thereto, and Bank of America, as administrative
agent, as amended or modified from time to time.

         "Unilab" means Unilab Corporation, a Delaware corporation, together
with its successors and assigns.


                                       22
<PAGE>
         "Unilab Acquisition" means the acquisition of a majority of the
outstanding shares (on a fully diluted basis) of common stock of Unilab pursuant
to the exchange offer contemplated by the Agreement and Plan of Merger dated as
of April 2, 2002 among the Borrower, Quest Diagnostics Newco Incorporated and
Unilab, and the merger of Unilab and Quest Diagnostics Newco Incorporated as
contemplated thereby.

         "Voting Stock" means all classes of the Capital Stock of such Person
then outstanding and normally entitled to vote in the election of directors (or
similar governing authority).

         1.2 COMPUTATION OF TIME PERIODS AND OTHER DEFINITIONAL PROVISIONS.

         For purposes of computation of periods of time hereunder, the word
"from" means "from and including" and the words "to" and "until" each mean "to
but excluding." References in this Credit Agreement to "Articles", "Sections",
"Schedules" or "Exhibits" shall be to Articles, Sections, Schedules or Exhibits
of or to this Credit Agreement unless otherwise specifically provided.

         1.3 ACCOUNTING TERMS/CALCULATION OF FINANCIAL COVENANTS.

                  (a) Except as otherwise expressly provided herein, all
         accounting terms used herein shall be interpreted, and all financial
         statements and certificates and reports as to financial matters
         required to be delivered to the Lenders hereunder shall be prepared, in
         accordance with GAAP applied on a consistent basis. All calculations
         made for the purposes of determining compliance with this Credit
         Agreement shall (except as otherwise expressly provided herein) be made
         by application of GAAP applied on a basis consistent with the most
         recent annual or quarterly financial statements delivered pursuant to
         Section 7.1 (or, prior to the delivery of the first financial
         statements pursuant to Section 7.1, consistent with the financial
         statements delivered to the Lenders prior to the Funding Date);
         provided, however, if (i) the Borrower shall object to determining such
         compliance on such basis at the time of delivery of such financial
         statements due to any change in GAAP or the rules promulgated with
         respect thereto or (ii) the Administrative Agent or the Required
         Lenders shall so object in writing within 30 days after delivery of
         such financial statements, then such calculations shall be made on a
         basis consistent with GAAP as in effect as of the date of the most
         recent financial statements delivered by the Borrower to the Lenders to
         which no such objection shall have been made.

                  (b) Notwithstanding anything herein to the contrary, for the
         purposes of calculating the financial covenants set forth in Section
         7.2, (i) income statement items (positive or negative) attributable to
         any Person or Property acquired in a Permitted Acquisition and
         Indebtedness incurred in connection with such Permitted Acquisition
         shall, without duplication, be treated as if such Person or Property
         was acquired or such Indebtedness incurred as of the first day of the
         twelve month period ending as of the most recently completely fiscal
         quarter of the Borrower and (ii) income statement items (positive or
         negative) attributable to Property disposed of in any asset sale
         permitted by Section 8.5(g) and Indebtedness retired in connection with
         such sale shall, without


                                       23
<PAGE>
         duplication, be treated as if such sale occurred as of the first day of
         the twelve month period ending as of the most recently completed fiscal
         quarter of the Borrower.

         1.4 TIME.

         All references to time herein shall be references to Eastern Standard
Time or Eastern Daylight time, as the case may be, unless specified otherwise.


                                    SECTION 2

                                 CREDIT FACILITY

         2.1 TERM LOANS.

                  (a) Term Loan. Subject to the terms and conditions set forth
         herein, each Lender severally agrees to make term loans (collectively,
         the "Term Loans" or "Loans") to the Borrower, in Dollars, in an amount
         equal to such Lender's Term Loan Commitment Percentage of the Term Loan
         Committed Amount; provided that the aggregate amount of such Term Loans
         made shall not exceed the Term Loan Committed Amount. Once repaid or
         prepaid, Term Loans cannot be reborrowed.

                  (b) Method of Borrowing Term Loans. By no later than 11:00
         a.m. (i) on the date of the requested borrowing if the Term Loans
         requested will be Base Rate Loans or (ii) three Business Days prior to
         the date of the requested borrowing if the Term Loans requested will be
         Eurodollar Loans, the Borrower shall provide telephonic notice to the
         Administrative Agent followed promptly by a written Notice of Borrowing
         in the form of Exhibit 2.1(b) (which may be submitted by telecopy),
         each of such telephonic notice and such written Notice of Borrowing
         setting forth (A) the amount requested, (B) whether such Term Loans
         shall be Base Rate Loans or Eurodollar Loans, (C) with respect to Term
         Loans that will be Eurodollar Loans, the Interest Period applicable
         thereto and (D) certification that the Borrower has complied in all
         respects with Section 5.3. Notwithstanding anything to the contrary
         herein, (x) the Borrower may not request more than two (2) borrowings
         under this Section 2.1 and (y) the Borrower may not request any
         borrowing subsequent to the date that is thirty (30) days after the
         Funding Date.

                  (c) Funding of Loans. Upon receipt of a Notice of Borrowing,
         the Administrative Agent shall promptly inform the Lenders as to the
         terms thereof. Each Lender shall make its Term Loan Commitment
         Percentage of the requested Term Loans available to the Administrative
         Agent by 1:00 p.m. on the date specified in the Notice of Borrowing by
         deposit, in Dollars, of immediately available funds at the Agency
         Services Address. The amount of the requested Term Loans will then be
         made available to the Borrower by the Administrative Agent as directed
         by the Borrower, to the extent the amount of such Term Loans are made
         available to the Administrative Agent.


                                       24
<PAGE>
                  No Lender shall be responsible for the failure or delay by any
         other Lender in its obligation to make Term Loans hereunder; provided,
         however, that the failure of any Lender to fulfill its obligations
         hereunder shall not relieve any other Lender of its obligations
         hereunder. Unless the Administrative Agent shall have been notified by
         any Lender prior to the date of any such Term Loan that such Lender
         does not intend to make available to the Administrative Agent its
         portion of the Term Loans to be made on such date, the Administrative
         Agent may assume that such Lender has made such amount available to the
         Administrative Agent on the date of such Term Loans, and the
         Administrative Agent in reliance upon such assumption, may (in its sole
         discretion but without any obligation to do so) make available to the
         Borrower a corresponding amount. If such corresponding amount is not in
         fact made available to the Administrative Agent, the Administrative
         Agent shall be able to recover such corresponding amount from such
         Lender. If such Lender does not pay such corresponding amount upon the
         Administrative Agent's demand therefor, the Administrative Agent will
         promptly notify the Borrower, and the Borrower shall immediately pay
         such corresponding amount to the Administrative Agent. The
         Administrative Agent shall also be entitled to recover from such Lender
         or the Borrower, as the case may be, interest on such corresponding
         amount in respect of each day from the date such corresponding amount
         was made available by the Administrative Agent to the Borrower to the
         date such corresponding amount is recovered by the Administrative Agent
         at a per annum rate equal to (i) from the Borrower at the applicable
         rate for such Term Loan pursuant to the Notice of Borrowing or (ii)
         from such Lender, at a rate per annum equal to, during the period to
         but excluding the date two Business Days after demand therefor, the
         Federal Funds Rate, and, thereafter, the Base Rate plus two percent
         (2%) per annum.

                  (d) Reductions of Term Loan Committed Amount. The Borrower
         shall have the right to permanently reduce, without premium or penalty,
         all or part of the aggregate unused amount of the Term Loan Committed
         Amount at any time or from time to time; provided that (i) each partial
         reduction shall be in an aggregate amount at least equal to $10,000,000
         and in integral multiples of $1,000,000 above such amount and shall be
         subject to Section 3.7, (ii) no reduction shall be made which would
         reduce the Term Loan Committed Amount to an amount less than the
         aggregate amount of outstanding Term Loans and (iii) each request for a
         reduction shall be made by the Borrower to the Administrative Agent in
         writing by no later than 11:00 a.m. on the date of the requested
         reduction. Any reduction in the Term Loan Committed Amount pursuant to
         this Section 2.1(d) shall be permanent and may not be reinstated. The
         Administrative Agent shall immediately notify the Lenders of any
         reduction in the Term Loan Committed Amount pursuant to this Section
         2.1(d).


                                       25
<PAGE>
                  (e) Amortization. Subject to Section 3.5, the principal amount
         of the Term Loans shall be repaid in quarterly payments on the dates
         set forth below:

<TABLE>
<CAPTION>
             Principal Amortization                  Term Loan Principal
                 Payment Dates                      Amortization Payments
<S>                                                 <C>
                    12/31/02                             $16,875,000
                    3/31/03                              $16,875,000
                    6/30/03                              $16,875,000
                    9/30/03                              $16,875,000
                    12/31/03                             $22,500,000
                    3/31/04                              $22,500,000
                    6/30/04                              $22,500,000
                    9/30/04                              $22,500,000
                    12/31/04                             $22,500,000
                    3/31/05                              $22,500,000
                    6/30/05                              $22,500,000
                    9/30/05                              $22,500,000
                    12/31/05                             $22,500,000
                    3/31/06                              $22,500,000
                    6/30/06                              $22,500,000
                    9/30/06                              $22,500,000
                    12/31/06                             $28,125,000
                    3/31/07                              $28,125,000
                 Maturity Date                           $56,250,000
</TABLE>


                  (f) Term Notes. The portion of the Term Loans made by each
         Lender shall be evidenced by a duly executed promissory note of the
         Borrower to each Lender that requests a Term Note in substantially the
         form of Exhibit 2.1(f).

         2.2 CONTINUATIONS AND CONVERSIONS.

         Subject to the terms below, the Borrower shall have the option, on any
Business Day, to continue existing Eurodollar Loans for a subsequent Interest
Period, to convert Base Rate Loans into Eurodollar Loans or to convert
Eurodollar Loans into Base Rate Loans. By no later than 11:00 a.m. (a) on the
date of the requested conversion of a Eurodollar Loan to a Base Rate Loan or (b)
three Business Days prior to the date of the requested continuation of a
Eurodollar Loan or conversion of a Base Rate Loan to a Eurodollar Loan, the
Borrower shall provide telephonic notice to the Administrative Agent, followed
promptly by a written Notice of Continuation/Conversion, in the form of Exhibit
2.2 setting forth (i) whether the Borrower wishes to continue or convert such
Loans and (ii) if the request is to continue a Eurodollar Loan or convert a Base
Rate Loan to a Eurodollar Loan, the Interest Period applicable thereto.
Notwithstanding anything herein to the contrary, (A) except as provided in
Section 3.11, Eurodollar Loans may only be continued or converted into Base Rate
Loans on the last day of the Interest Period applicable thereto, (B) Eurodollar
Loans may not be continued nor may Base Rate Loans be converted into Eurodollar
Loans during the existence and continuation of a Default or an Event of Default,
(C) any request to continue a Eurodollar Loan that fails to comply with the
terms hereof or any failure to request a


                                       26
<PAGE>
continuation of a Eurodollar Loan at the end of an Interest Period shall
constitute a conversion to a Base Rate Loan on the last day of the applicable
Interest Period and (D) any failure to state the Interest Period with respect to
the continuation of a Eurodollar Loan or the conversion of a Base Rate Loan to a
Eurodollar Loan shall constitute a request for a one month Interest Period.

         2.3 MINIMUM AMOUNTS.

         Each request for a borrowing, conversion or continuation shall be
subject to the requirements that (a) each Eurodollar Loan shall be in a minimum
amount of $10,000,000 and in integral multiples of $1,000,000 in excess thereof,
(b) each Base Rate Loan shall be in a minimum amount of the lesser of $5,000,000
(and in integral multiples of $1,000,000 in excess thereof) or the remaining
amount available under the Term Loan Committed Amount and (c) no more than ten
Eurodollar Loans shall be outstanding hereunder at any one time. For the
purposes of this Section 2.3, all Eurodollar Loans with the same Interest
Periods that begin and end on the same date shall be considered as one
Eurodollar Loan, but Eurodollar Loans with different Interest Periods, even if
they begin on the same date, shall be considered as separate Eurodollar Loans.

                                    SECTION 3

                     GENERAL PROVISIONS APPLICABLE TO LOANS

         3.1 INTEREST.

                  (a) Interest Rate. Subject to Section 3.1(b), (i) all Base
         Rate Loans shall accrue interest at the Base Rate and (ii) all
         Eurodollar Loans shall accrue interest at the Adjusted Eurodollar Rate.

                  (b) Default Rate of Interest. Upon the occurrence, and during
         the continuation, of an Event of Default pursuant to Section 9.1(a),
         the principal of and, to the extent permitted by law, interest on the
         Loans and any other amounts owing hereunder or under the other Credit
         Documents (including without limitation fees and expenses) shall bear
         interest, payable on demand, at a per annum rate equal to 2% plus the
         rate which would otherwise be applicable (or if no rate is applicable,
         then the Base Rate plus two percent (2%) per annum).

                  (c) Interest Payments. Interest on Loans shall be due and
         payable in arrears on each Interest Payment Date.

         3.2 PLACE AND MANNER OF PAYMENTS.

         All payments of principal, interest, fees, expenses and other amounts
to be made by a Credit Party under this Credit Agreement shall be made
unconditionally and without any setoff, deduction, counterclaim, defense,
recoupment or withholding of any kind and received not later than 2:00 p.m. on
the date when due, in Dollars and in immediately available funds, by the
Administrative Agent at the Agency Services Address. Payments received after
such time shall be deemed to have been received on the next Business Day. The
Borrower shall, at the time it makes any payment under


                                       27
<PAGE>
this Credit Agreement, specify to the Administrative Agent the Loans, fees or
other amounts payable by the Borrower hereunder to which such payment is to be
applied (and in the event that it fails to specify, or if such application would
be inconsistent with the terms hereof, the Administrative Agent shall, subject
to Section 3.7, distribute such payment to the Lenders in such manner as the
Administrative Agent may reasonably deem appropriate). The Administrative Agent
will distribute such payments to the Lenders on the same Business Day if any
such payment is received at or before 2:00 p.m.; otherwise the Administrative
Agent will distribute such payment to the Lenders on the next succeeding
Business Day. Whenever any payment hereunder shall be stated to be due on a day
which is not a Business Day, the due date thereof shall be extended to the next
succeeding Business Day (subject to accrual of interest and fees for the period
of such extension), except that, in the case of Eurodollar Loans (or interest
payable with respect thereto), if the extension would cause the payment to be
made in the next following calendar month, then such payment shall instead be
made on the next preceding Business Day.

         3.3 PREPAYMENTS; REVISION OF AMORTIZATION SCHEDULE.

                  (a) Voluntary Prepayments. The Borrower shall have the right
         to prepay Loans in whole or in part from time to time without premium
         or penalty; provided, however, that (i) Eurodollar Loans may only be
         prepaid on three Business Days' prior written notice to the
         Administrative Agent and (ii) each such partial prepayment of
         Eurodollar Loans or Base Rate Loans shall be in the minimum principal
         amount of $5,000,000 and integral multiples of $1,000,000. Amounts
         prepaid pursuant to this Section 3.3(a) shall be applied (A) first to
         the next scheduled amortization payment set forth in Section 2.1(e) and
         (B) second to the remaining scheduled amortization payments set forth
         in Section 2.1(e) on a pro rata basis. Within the foregoing parameters,
         amounts prepaid pursuant to this Section 3.3(a) shall be applied first
         to Base Rate Loans and then to Eurodollar Loans in direct order of
         Interest Period maturities. All prepayments under this Section 3.3(a)
         shall be subject to Section 3.14.

                  (b) Revision of Amortization Schedule. If the Borrower reduces
         the Term Loan Committed Amount pursuant to Section 2.1(d) or makes a
         prepayment in accordance with this Section 3.3, the Administrative
         Agent shall recalculate the outstanding principal amount of the Term
         Loans following such prepayment (as applicable), reschedule the
         remaining amortization payments giving effect to such reduction or
         prepayment, and promptly distribute to the Borrower and to each of the
         Lenders a revised version of the schedule which appears in Section
         2.1(e). Any reduction of the amortization payments set forth in Section
         2.1(e) as a result of a reduction of the Term Loan Committed Amount
         pursuant to Section 2.1(d) shall be made on a pro rata basis with
         respect to the remaining scheduled amortization payments.

         3.4 FEES.

         The Borrower agrees to pay to the Administrative Agent, for its own
account, an annual fee as agreed to between the Borrower and the Administrative
Agent (the "Administrative Fees"). Each of the Lenders agrees that any upfront
fee paid to such Lender by the Borrower or Bank of America with respect to its
Commitment shall be based on the amount of such Lender's Commitment


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<PAGE>
immediately prior to the initial funding of Term Loans and after giving effect
to any reduction of the Term Loan Committed Amount pursuant to Section 2.1(d) on
the date of such initial funding.

         3.5 PAYMENT IN FULL AT MATURITY OR OTHERWISE.

         The entire outstanding principal balance of all Loans, together with
accrued but unpaid interest and all other sums owing with respect thereto, shall
be due and payable in full, unless accelerated sooner pursuant to Section 9 on
the earlier of (a) the Maturity Date or (b) the date that is 30 days after the
Funding Date if the Unilab Acquisition has not been consummated prior to such
date.

         3.6 COMPUTATIONS OF INTEREST AND FEES.

                  (a) Except for Base Rate Loans that are based upon the Prime
         Rate, in which case interest shall be computed on the basis of the
         actual number of days elapsed over a year of 365 or 366 days, as the
         case may be, all computations of interest and fees hereunder shall be
         made on the basis of the actual number of days elapsed over a year of
         360 days. Interest shall accrue from and include the date of borrowing
         (or continuation or conversion) but exclude the date of payment.

                  (b) It is the intent of the Lenders and the Credit Parties to
         conform to and contract in strict compliance with applicable usury law
         from time to time in effect. All agreements between the Lenders and the
         Credit Parties are hereby limited by the provisions of this paragraph
         which shall override and control all such agreements, whether now
         existing or hereafter arising and whether written or oral. In no way,
         nor in any event or contingency (including but not limited to
         prepayment or acceleration of the maturity of any obligation), shall
         the interest taken, reserved, contracted for, charged, or received
         under this Credit Agreement, under the Notes or otherwise, exceed the
         maximum nonusurious amount permissible under applicable law. If, from
         any possible construction of any of the Credit Documents or any other
         document, interest would otherwise be payable in excess of the maximum
         nonusurious amount, any such construction shall be subject to the
         provisions of this paragraph and such documents shall be automatically
         reduced to the maximum nonusurious amount permitted under applicable
         law, without the necessity of execution of any amendment or new
         document. If any Lender shall ever receive anything of value which is
         characterized as interest on the Loans under applicable law and which
         would, apart from this provision, be in excess of the maximum
         nonusurious amount, an amount equal to the amount which would have been
         excessive interest shall, without penalty, be applied to the reduction
         of the principal amount owing on the Loans and not to the payment of
         interest, or refunded to the Borrower or the other payor thereof if and
         to the extent such amount which would have been excessive exceeds such
         unpaid principal amount of the Loans. The right to demand payment of
         the Loans or any other Indebtedness evidenced by any of the Credit
         Documents does not include the right to accelerate the payment of any
         interest which has not otherwise accrued on the date of such demand,
         and the Lenders do not intend to charge or receive any unearned
         interest in the event of such demand. All interest paid or agreed to be
         paid to the Lenders with respect to the Loans shall, to the extent
         permitted by applicable law, be amortized, prorated, allocated, and
         spread throughout the full stated term (including


                                       29
<PAGE>
         any renewal or extension) of the Loans so that the amount of interest
         on account of such Indebtedness does not exceed the maximum nonusurious
         amount permitted by applicable law.

         3.7 PRO RATA TREATMENT.

         Except to the extent otherwise provided herein, each Term Loan
borrowing, each payment or prepayment of principal of any Term Loan, each
reduction of the Term Loan Committed Amount, each payment of fees (other than
the Administrative Fees retained by the Administrative Agent for its own
account), and each conversion or continuation of any Term Loan shall (except as
otherwise provided in Section 3.11) be allocated pro rata among the Lenders in
accordance with the Term Loan Commitment Percentages of the Lenders (or, if the
Commitments of the Lenders have expired or been terminated, in accordance with
the respective principal amounts of the outstanding Term Loans and Participation
Interests of the Lenders); provided that, if any Lender shall have failed to
fund its applicable pro rata share of any Term Loan, then any amount to which
such Lender would otherwise be entitled pursuant to this Section 3.7 shall
instead be payable to the Administrative Agent until the share of such Loan not
funded by such Lender has been repaid; provided further, that in the event any
amount paid to any Lender pursuant to this Section 3.7 is rescinded or must
otherwise be returned by the Administrative Agent, each Lender shall, upon the
request of the Administrative Agent, repay to the Administrative Agent the
amount so paid to such Lender, with interest for the period commencing on the
date such payment is returned by the Administrative Agent until the date the
Administrative Agent receives such repayment at a rate per annum equal to,
during the period to but excluding the date two Business Days after such
request, the Federal Funds Rate, and thereafter, the Base Rate plus two percent
(2%) per annum.

         3.8 SHARING OF PAYMENTS.

         The Lenders agree among themselves that, except to the extent otherwise
provided herein, in the event that any Lender shall obtain payment in respect of
any Loan, or any other obligation owing to such Lender under this Credit
Agreement through the exercise of a right of setoff, banker's lien or
counterclaim, or pursuant to a secured claim under Section 506 of the Bankruptcy
Code or other security or interest arising from, or in lieu of, such secured
claim, received by such Lender under any applicable bankruptcy, insolvency or
other similar law or otherwise, or by any other means, in excess of its pro rata
share of such payment as provided for in this Credit Agreement, such Lender
shall promptly pay in cash or purchase from the other Lenders a participation in
such Loans, and other obligations in such amounts, and make such other
adjustments from time to time, as shall be equitable to the end that all Lenders
share such payment in accordance with their respective ratable shares as
provided for in this Credit Agreement. The Lenders further agree among
themselves that if payment to a Lender obtained by such Lender through the
exercise of a right of setoff, banker's lien, counterclaim or other event as
aforesaid shall be rescinded or must otherwise be restored, each Lender which
shall have shared the benefit of such payment shall, by payment in cash or a
repurchase of a participation theretofore sold, return its share of that benefit
(together with its share of any accrued interest payable with respect thereto)
to each Lender whose payment shall have been rescinded or otherwise restored.
The Borrower agrees that any Lender so purchasing such a participation may, to
the fullest extent permitted by law, exercise all rights of payment, including
setoff, banker's lien or counterclaim, with respect to such participation as
fully


                                       30
<PAGE>
as if such Lender were a holder of such Loan, or other obligation in the amount
of such participation. Except as otherwise expressly provided in this Credit
Agreement, if any Lender or the Administrative Agent shall fail to remit to any
other Lender an amount payable by such Lender or the Administrative Agent to
such other Lender pursuant to this Credit Agreement on the date when such amount
is due, such payments shall be made together with interest thereon for each date
from the date such amount is due until the date such amount is paid to the
Administrative Agent or such other Lender at a rate per annum equal to the
Federal Funds Rate. If under any applicable bankruptcy, insolvency or other
similar law, any Lender receives a secured claim in lieu of a setoff to which
this Section 3.8 applies, such Lender shall, to the extent practicable, exercise
its rights in respect of such secured claim in a manner consistent with the
rights of the Lenders under this Section 3.8 to share in the benefits of any
recovery on such secured claim.

         3.9 CAPITAL ADEQUACY/REGULATION D.

                  (a) If, after the date thereof, any Lender determines that the
         introduction after the Closing Date of any law, rule or regulation or
         other Requirement of Law regarding capital adequacy or any change
         therein or in the interpretation thereof, or compliance by such Lender
         (or its Lending Office) therewith, has or would have the effect of
         reducing the rate of return on the capital or assets of such Lender or
         any corporation controlling such Lender as a consequence of such
         Lender's obligations hereunder (taking into consideration its policies
         with respect to capital adequacy and such Lender's desired return on
         capital), then from time to time upon demand of such Lender (with a
         copy of such demand to the Administrative Agent), the Borrower shall
         pay to such Lender such additional amounts as will compensate such
         Lender for such reduction.

                  (b) The Borrower shall pay to each Lender, as long as such
         Lender shall be required under regulations of the Board of Governors of
         the Federal Reserve System of the United States of America to maintain
         reserves with respect to liabilities or assets consisting of or
         including Eurocurrency funds or deposits (currently known as
         "Eurocurrency liabilities"), additional interest on the unpaid
         principal amount of each Eurodollar Loan equal to (i) (A) the
         applicable Eurodollar Rate divided by (B) one minus the Eurodollar
         Reserve Percentage minus (ii) the applicable Eurodollar Rate. Such
         additional interest shall be due and payable on each date on which
         interest is payable on such Loan; provided the Borrower shall have
         received at least five days' prior notice (with a copy to the
         Administrative Agent) of such additional interest from such Lender. If
         a Lender fails to give notice five days prior to the relevant Interest
         Payment Date, such additional interest shall be due and payable five
         days from the receipt by the Borrower of such notice.

         3.10     INABILITY TO DETERMINE INTEREST RATE.

         If the Administrative Agent determines (which determination shall be
conclusive and binding upon the Borrower) in connection with any request for a
Eurodollar Loan or a conversion to or continuation of a Eurodollar Loan that (a)
Dollar deposits are not being offered to banks in the applicable offshore Dollar
market for the applicable amount and Interest Period of such Eurodollar Loan,
(b) adequate and reasonable means do not exist for determining the Eurodollar
Rate for such Eurodollar Loan, or (c) the Eurodollar Rate for such Eurodollar
Loan


                                       31
<PAGE>
does not adequately and fairly reflect the cost to the Lenders of funding such
Eurodollar Loan, the Administrative Agent will promptly notify the Borrower and
all the Lenders. Thereafter, the obligation of the Lenders to make or maintain
Eurodollar Loans shall be suspended until the Administrative Agent revokes such
notice. Upon receipt of such notice, the Borrower may revoke any pending Notice
of Borrowing or Notice of Continuation/Conversion with respect to Eurodollar
Loans or, failing that, will be deemed to have converted such request into a
request for a borrowing of or conversion into a Base Rate Loan in the amount
specified therein.

         3.11 ILLEGALITY.

         If any Lender determines that any Requirement of Law has made it
unlawful, or that any Governmental Authority has asserted that it is unlawful,
for any Lender or its applicable Lending Office to make, maintain or fund
Eurodollar Loans, or materially restricts the authority of such Lender to
purchase or sell, or to take deposits of, Dollars in the applicable offshore
Dollar market, or to determine or charge interest rates based upon the
Eurodollar Rate, then, on notice thereof by such Lender to the Borrower through
the Administrative Agent, any obligation of such Lender to make or continue
Eurodollar Loans or to convert Base Rate Loans to Eurodollar Loans shall be
suspended until such Lender notifies the Administrative Agent and the Borrower
that the circumstances giving rise to such determination no longer exist. Upon
receipt of such notice, the Borrower shall, upon demand from such Lender (with a
copy to the Administrative Agent), prepay or, if applicable, convert all
Eurodollar Loans of such Lender to Base Rate Loans, either on the last day of
the Interest Period thereof, if such Lender may lawfully continue to maintain
such Eurodollar Loans to such day, or immediately, if such Lender may not
lawfully continue to maintain such Eurodollar Loans. Upon any such prepayment or
conversion, the Borrower shall also pay interest on the amount so prepaid or
converted, together with any amounts due with respect thereto pursuant to
Section 3.14. Each Lender agrees to designate a different Lending Office if such
designation will avoid the need for such notice and will not, in the good faith
judgment of such Lender, otherwise be materially disadvantageous to such Lender.

         3.12 REQUIREMENTS OF LAW.

         If any Lender determines that as a result of the introduction of or any
change in, or in the interpretation of, any Requirement of Law, or such Lender's
compliance therewith, there shall be any increase in the cost to such Lender of
agreeing to make or making, funding or maintaining Eurodollar Loans or a
reduction in the amount received or receivable by such Lender in connection with
any of the foregoing (excluding for purposes of this subsection (a) any such
increased costs or reduction in amount resulting from (i) Taxes or Other Taxes
(as to which Section 3.13 shall govern) and (ii) reserve requirements referred
to in Section 3.9(b), then from time to time, within 10 days of demand of such
Lender (with a copy of such demand to the Administrative Agent), the Borrower
shall pay to such Lender such additional amounts as will compensate such Lender
for such increased cost or reduction in yield.


                                       32
<PAGE>
         3.13 TAXES.

                  (a) Any and all payments by a Credit Party to or for the
         account of the Administrative Agent or any Lender under any Credit
         Document shall be made free and clear of and without deduction for any
         and all present or future income, stamp or other taxes, duties, levies,
         imposts, deductions, assessments, fees, withholdings or similar
         charges, and all liabilities with respect thereto, but excluding, in
         the case of the Administrative Agent and each Lender, taxes imposed on
         or measured by its net income, and franchise taxes imposed on it (in
         lieu of net income taxes), by the jurisdiction (or any political
         subdivision thereof) under the laws of which the Administrative Agent
         or such Lender, as the case may be, is organized or maintains its
         Lending Office (all such non-excluded present or future income, stamp
         or other taxes, duties, levies, imposts, deductions, assessments, fees,
         withholdings or similar charges, and liabilities being hereinafter
         referred to as "Taxes"). If a Credit Party shall be required by any
         Requirement of Law to deduct any Taxes from or in respect of any sum
         payable under any Credit Document to the Administrative Agent or any
         Lender, (i) the sum payable shall be increased as necessary so that
         after making all required deductions (including deductions applicable
         to additional sums payable under this Section 3.13(a)), the
         Administrative Agent or such Lender, as the case may be, receives an
         amount equal to the sum it would have received had no such deductions
         been made, (ii) such Credit Party shall make such deductions, (iii)
         such Credit Party shall pay the full amount deducted to the relevant
         taxation authority or other Governmental Authority in accordance with
         applicable Requirements of Law, and (iv) within 30 days after the date
         of such payment, such Credit Party shall furnish to the Administrative
         Agent (which shall forward the same to such Lender) the original or a
         certified copy of a receipt evidencing payment thereof, to the extent
         such receipt is issued therefor, or other written proof of payment
         thereof that is reasonably satisfactory to the Administrative Agent.

                  (b) In addition, each Credit Party agrees to pay any and all
         present or future stamp, court or documentary taxes and any other
         excise or property taxes or charges or similar levies which arise from
         any payment made under any Credit Document or from the execution,
         delivery, performance, enforcement or registration of, or otherwise
         with respect to, any Credit Document (hereinafter referred to as "Other
         Taxes").

                  (c) If a Credit Party shall be required to deduct or pay any
         Taxes or Other Taxes from or in respect of any sum payable under any
         Credit Document to the Administrative Agent or any Lender, such Credit
         Party shall also pay to the Administrative Agent (for the account of
         such Lender) or to such Lender, at the time interest is paid, such
         additional amount that such Lender reasonably specifies by written
         notice to such Credit Party as necessary to preserve the after-tax
         yield (after factoring in all taxes, including taxes imposed on or
         measured by net income) such Lender would have received if such Taxes
         or Other Taxes had not been imposed; provided that if such Lender fails
         to provide such notice to such Credit Party before the date which is
         five days prior to the date such interest is paid, such Credit Party
         shall pay at the time such interest is paid such amount as such Credit
         Party reasonably estimates will preserve such


                                       33
<PAGE>
         Lender's after-tax yield (after factoring in only such Taxes or Other
         Taxes) and pay the balance within five days after receiving such
         notice.

                  (d) Each Credit Party agrees to indemnify the Administrative
         Agent and each Lender for (i) the full amount of Taxes and Other Taxes
         (including any Taxes or Other Taxes imposed or asserted by any
         jurisdiction on amounts payable under this Section 3.13(d)) paid by the
         Administrative Agent and such Lender, and (ii) any liability (including
         penalties, interest and reasonable expenses) arising therefrom or with
         respect thereto.

                  (e) In the case of any payment hereunder or under any other
         Credit Document by or on behalf of a Credit Party through an account or
         branch outside the United States, or on behalf of a Credit Party by a
         payor that is not a United States person, if such Credit Party
         determines that no taxes are payable in respect thereof, such Credit
         Party shall furnish, or shall cause such payor to furnish, to the
         Administrative Agent, an opinion of counsel reasonably acceptable to
         the Administrative Agent stating that such payment is exempt from
         Taxes. For purposes of this subsection (e), the terms "United States"
         and "United States person" shall have the meanings specified in Section
         7701 of the Code.

                  (f) Each Lender that is a foreign corporation, foreign
         partnership or foreign trust within the meaning of the Code shall
         deliver to the Administrative Agent, prior to receipt of any payment
         subject to withholding under the Code, two duly signed completed copies
         of either IRS Form W-8BEN or any successor thereto (relating to such
         Lender and entitling it to an exemption from, or reduction of,
         withholding tax on all payments to be made to such Lender by the Credit
         Parties pursuant to this Credit Agreement) or IRS Form W-8ECI or any
         successor thereto (relating to all payments to be made to such Lender
         by a Credit Party pursuant to this Credit Agreement), as appropriate,
         or such other evidence satisfactory to the Borrower and the
         Administrative Agent that such Lender is entitled to an exemption from,
         or reduction of, United States withholding tax. Thereafter and from
         time to time, each such Lender shall (i) promptly submit to the
         Administrative Agent such additional duly completed and signed copies
         of one of such forms (or such successor forms as shall be adopted from
         time to time by the relevant United States taxing authorities), as
         appropriate, as may reasonably be requested by the Borrower or the
         Administrative Agent and then be available under then current United
         States laws and regulations to avoid, or such evidence as is
         satisfactory to the Borrower and the Administrative Agent of any
         available exemption from or reduction of, United States withholding
         taxes in respect of all payments to be made to such Lender by the
         Borrower pursuant to this Credit Agreement, (ii) promptly notify the
         Administrative Agent of any change in circumstances which would modify
         or render invalid any claimed exemption or reduction, and (iii) take
         such steps as shall not be materially disadvantageous to it, in the
         reasonable judgment of such Lender, and as may be reasonably necessary
         (including the re-designation of its Lending Office) to avoid any
         Requirement of Law that the Credit Parties make any deduction or
         withholding for taxes from amounts payable to such Lender. If the forms
         or other evidence provided by such Lender at the time such Lender first
         becomes a party to this Credit Agreement indicate a United States
         interest withholding tax rate in excess of zero, withholding tax at
         such rate


                                       34
<PAGE>
         shall be considered excluded from Taxes unless and until such Lender
         provides the appropriate forms certifying that a lesser rate applies,
         whereupon withholding tax at such lesser rate only shall be considered
         excluded from Taxes for periods governed by such forms; provided,
         however, that, if at the date of any assignment pursuant to which a
         Lender becomes a party to this Credit Agreement, the Lender assignor
         was entitled to payments under subsection (a) of this Section 3.13 in
         respect of United States withholding tax with respect to interest paid
         at such date, then, to such extent, the term Taxes shall include (in
         addition to withholding taxes that may be imposed in the future or
         other amounts otherwise includable in Taxes) United States withholding
         tax, if any, applicable with respect to the Lender assignee on such
         date. If such Lender fails to deliver the above forms or other
         evidence, then the Administrative Agent may withhold from any interest
         payment to such Lender an amount equal to the applicable withholding
         tax imposed by Sections 1441 and 1442 of the Code, without reduction.
         If any Governmental Authority asserts that the Administrative Agent did
         not properly withhold any tax or other amount from payments made in
         respect of such Lender, such Lender shall indemnify the Administrative
         Agent therefor, including all penalties and interest, any taxes imposed
         by any jurisdiction on the amounts payable to the Administrative Agent
         under this Section 3.13(f), and costs and expenses (including Attorney
         Costs) of the Administrative Agent. For any period with respect to
         which a Lender has failed to provide the Borrower with the above forms
         or other evidence (other than if such failure is due to a change in the
         applicable law, or in the interpretation or application thereof,
         occurring after the date on which such form or other evidence
         originally was required to be provided or if such form or other
         evidence otherwise is not required, such Lender shall not be entitled
         to indemnification under subsection (a) or (c) of this Section 3.13
         with respect to Taxes imposed by the United States by reason of such
         failure; provided, however, that should a Lender become subject to
         Taxes because of its failure to deliver such form or other evidence
         required hereunder, the Borrower shall take such steps as such Lender
         shall reasonably request to assist such Lender in recovering such
         Taxes. The obligation of the Lenders under this Section 3.13(f) shall
         survive the payment of all Credit Party Obligations and the resignation
         or replacement of the Administrative Agent.

               (g) In the event that an additional payment is made under Section
         3.13(a) or (c) for the account of any Lender and such Lender, in its
         reasonable judgment, determines that it has finally and irrevocably
         received or been granted a credit against or release or remission for,
         or repayment of, any tax paid or payable by it in respect of or
         calculated with reference to the deduction or withholding giving rise
         to such payment, such Lender shall, to the extent that it determines
         that it can do so without prejudice to the retention of the amount of
         such credit, relief, remission or repayment, pay to the Borrower such
         amount as such Lender shall, in its reasonable judgment, have
         determined to be attributable to such deduction or withholding and
         which will leave such Lender (after such payment) in no worse position
         than it would have been in if the Borrower had not been required to
         make such deduction or withholding. Nothing herein contained shall
         interfere with the right of a Lender to arrange its tax affairs in
         whatever manner it thinks fit nor oblige any Lender to claim any tax
         credit or to disclose any information relating to its tax affairs or
         any computations in respect thereof or require any Lender to do
         anything


                                       35

<PAGE>
         that would prejudice its ability to benefit from any other credits,
         reliefs, remissions or repayments to which it may be entitled.

         3.14     COMPENSATION.

         Upon the written demand of any Lender, the Borrower shall promptly
compensate such Lender for and hold such Lender harmless from any loss, cost or
expense incurred by it as a result of:

                  (a)      any continuation, conversion, payment or prepayment
         of any Eurodollar Loan on a day other than the last day of the Interest
         Period for such Eurodollar Loan (whether voluntary, mandatory,
         automatic, by reason of acceleration, or otherwise); or

                  (b)      any failure by the Borrower (for a reason other than
         the failure of such Lender to make a Eurodollar Loan) to prepay,
         borrow, continue or convert any Eurodollar Loan on the date or in the
         amount previously requested by the Borrower.

The amount each such Lender shall be compensated pursuant to this Section 3.14
shall include, without limitation, (i) any loss incurred by such Lender in
connection with the re-employment of funds prepaid, repaid, not borrowed or
paid, as the case may be and (ii) any reasonable out-of-pocket expenses
(including Attorney Costs) incurred and reasonably attributable thereto.

For purposes of calculating amounts payable by the Borrower to the Lenders under
this Section 3.14, each Lender may deem that it funded each Eurodollar Loan made
by it at the Eurodollar Rate for such Eurodollar Loan by a matching deposit or
other borrowing in the applicable offshore Dollar interbank market for a
comparable amount and for a comparable period, whether or not such Eurodollar
Loan was in fact so funded.

         3.15     DETERMINATION AND SURVIVAL OF PROVISIONS.

         All determinations by the Administrative Agent or a Lender of amounts
owing under Sections 3.9 through 3.14, inclusive, shall, absent manifest error,
be conclusive and binding on the parties hereto. In determining such amount, the
Administrative Agent or such Lender may use any reasonable averaging and
attribution methods. Sections 3.9 through 3.14, inclusive, shall survive the
termination of this Credit Agreement and the payment of all Credit Party
Obligations.

         3.16     NOTIFICATION BY LENDERS.

         Subject to Section 3.13(c), each Lender shall notify the Borrower (and
any applicable Credit Party) of any event that will entitle such Lender to
compensation under Section 3.9, 3.12, 3.13 or 3.14 as promptly as practicable,
but in any event within 90 days after such Lender obtains actual knowledge
thereof; provided, however, that if any Lender fails to give such notice within
90 days after it obtains actual knowledge of such an event, such Lender shall,
with respect to compensation payable pursuant to Section 3.9, 3.12, 3.13 or 3.14
in respect of any costs resulting from such event, only be entitled to payment
under Section 3.9, 3.12, 3.13 or 3.14 for costs incurred from and after the date
90 days prior to the date that such Lender gives such notice. If


                                       36
<PAGE>
requested by the Borrower, each Lender will furnish to Borrower within ten
Business Days of the time the Lender requests compensation under Section 3.9,
3.12, 3.13 or 3.14, a certificate setting forth the basis, amount and reasonable
detail of computation of each request by such Lender for compensation under
Section 3.9, 3.12, 3.13 or 3.14, which certificate shall, except for
demonstrable error, be final, conclusive and binding for all purposes.

         3.17     MITIGATION; MANDATORY ASSIGNMENT.

         Each Lender shall use reasonable efforts to avoid or mitigate any
increased cost or suspension of the availability of an interest rate under
Sections 3.9 through 3.14 above to the greatest extent practicable (including
transferring the Loans to another Lending Office or Affiliate of a Lender)
unless, in the reasonable opinion of such Lender, such efforts would be likely
to have an adverse effect upon it. In the event a Lender makes a request to the
Borrower for additional payments in accordance with Section 3.9, 3.11, 3.12,
3.13 or 3.14, then, provided that no Default or Event of Default has occurred
and is continuing at such time, the Borrower may, at its own expense (such
expense to include, without limitation, any transfer fee payable to the
Administrative Agent under Section 11.3(b)) and in its sole discretion, require
such Lender to transfer and assign in whole (but not in part), without recourse
(in accordance with and subject to the terms and conditions of Section 11.3(b)),
all of its interests, rights and obligations under this Credit Agreement to an
Eligible Assignee which shall assume such assigned obligations (which assignee
may be another Lender, if a Lender accepts such assignment); provided that (a)
such assignment shall not conflict with any law, rule or regulation or order of
any court or other Governmental Authority and (b) the Borrower or such assignee
shall have paid to the assigning Lender in immediately available funds the
principal of and interest accrued to the date of such payment on the portion of
the Loans hereunder held by such assigning Lender and all other amounts owed to
such assigning Lender hereunder, including amounts owed pursuant to Sections 3.9
through 3.14 hereof.

                                    SECTION 4

                                    GUARANTY

         4.1      GUARANTY OF PAYMENT.

         Subject to Section 4.7 below, each of the Guarantors hereby, jointly
and severally, unconditionally guarantees to each Lender and the Administrative
Agent the prompt payment of the Credit Party Obligations in full when due
(whether at stated maturity, as a mandatory prepayment, by acceleration or
otherwise) and the timely performance of all other obligations under the Credit
Documents. This Guaranty is a guaranty of payment and not of collection and is a
continuing guaranty and shall apply to all Credit Party Obligations whenever
arising.

         4.2      OBLIGATIONS UNCONDITIONAL.

         The obligations of the Guarantors hereunder are absolute and
unconditional, irrespective of the value, genuineness, validity, regularity or
enforceability of any of the Credit Documents, or any


                                       37
<PAGE>
other agreement or instrument referred to therein, to the fullest extent
permitted by applicable law, irrespective of any other circumstance whatsoever
which might otherwise constitute a legal or equitable discharge or defense of a
surety or guarantor. Each Guarantor agrees that this Guaranty may be enforced by
the Lenders without the necessity at any time of resorting to or exhausting any
other security or collateral and without the necessity at any time of having
recourse to the Notes or any other of the Credit Documents or any collateral, if
any, hereafter securing the Credit Party Obligations or otherwise and each
Guarantor hereby waives the right to require the Lenders to proceed against the
Borrower or any other Person (including a co-guarantor) or to require the
Lenders to pursue any other remedy or enforce any other right. Each Guarantor
further agrees that it shall have no right of subrogation, indemnity,
reimbursement or contribution against the Borrower or any other Guarantor of the
Credit Party Obligations for amounts paid under this Guaranty until such time as
the Lenders have been paid in full and all Commitments under the Credit
Agreement have been terminated. Each Guarantor further agrees that nothing
contained herein shall prevent the Lenders from suing on the Notes or any of the
other Credit Documents or foreclosing its security interest in or Lien on any
collateral, if any, securing the Credit Party Obligations or from exercising any
other rights available to it under this Credit Agreement, the Notes, any other
of the Credit Documents, or any other instrument of security, if any, and the
exercise of any of the aforesaid rights and the completion of any foreclosure
proceedings shall not constitute a discharge of any of such Guarantor's
obligations hereunder; it being the purpose and intent of each Guarantor that
its obligations hereunder shall be absolute, independent and unconditional under
any and all circumstances. Neither any Guarantor's obligations under this
Guaranty nor any remedy for the enforcement thereof shall be impaired, modified,
changed or released in any manner whatsoever by an impairment, modification,
change, release or limitation of the liability of the Borrower or by reason of
the bankruptcy or insolvency of the Borrower. Each Guarantor waives any and all
notice of the creation, renewal, extension or accrual of any of the Credit Party
Obligations and notice of or proof of reliance of by the Administrative Agent or
any Lender upon this Guaranty or acceptance of this Guaranty. The Credit Party
Obligations, and any of them, shall conclusively be deemed to have been created,
contracted or incurred, or renewed, extended, amended or waived, in reliance
upon this Guaranty. All dealings between the Borrower and any of the Guarantors,
on the one hand, and the Administrative Agent and the Lenders, on the other
hand, likewise shall be conclusively presumed to have been had or consummated in
reliance upon this Guaranty. The Guarantors further agree to all rights of
set-off as set forth in Section 11.2.

         4.3      MODIFICATIONS.

         Each Guarantor agrees that (a) all or any part of the collateral, if
any, now or hereafter held for the Credit Party Obligations, if any, may be
exchanged, compromised or surrendered from time to time; (b) the Lenders shall
not have any obligation to protect, perfect, secure or insure any such security
interests, liens or encumbrances now or hereafter held, if any, for the Credit
Party Obligations or the properties subject thereto; (c) the time or place of
payment of the Credit Party Obligations may be changed or extended, in whole or
in part, to a time certain or otherwise, and may be renewed or accelerated, in
whole or in part; (d) the Borrower and any other party liable for payment under
the Credit Documents may be granted indulgences generally; (e) any of the
provisions of the Notes or any of the other Credit Documents may be modified,
amended or waived; (f) any party (including any co-guarantor) liable for the
payment thereof may be granted indulgences or be released; and (g) any deposit
balance for the credit of the Borrower or any other


                                       38
<PAGE>
party liable for the payment of the Credit Party Obligations or liable upon any
security therefor may be released, in whole or in part, at, before or after the
stated, extended or accelerated maturity of the Credit Party Obligations, all
without notice to or further assent by such Guarantor, which shall remain bound
thereon, notwithstanding any such exchange, compromise, surrender, extension,
renewal, acceleration, modification, indulgence or release.

         4.4      WAIVER OF RIGHTS.

         Each Guarantor expressly waives to the fullest extent permitted by
applicable law: (a) notice of acceptance of this Guaranty by the Lenders and of
all extensions of credit to the Borrower by the Lenders; (b) presentment and
demand for payment or performance of any of the Credit Party Obligations; (c)
protest and notice of dishonor or of default (except as specifically required in
the Credit Agreement) with respect to the Credit Party Obligations or with
respect to any security therefor; (d) notice of the Lenders obtaining, amending,
substituting for, releasing, waiving or modifying any security interest, lien or
encumbrance, if any, hereafter securing the Credit Party Obligations, or the
Lenders' subordinating, compromising, discharging or releasing such security
interests, liens or encumbrances, if any; and (e) all other notices to which
such Guarantor might otherwise be entitled.

         4.5      REINSTATEMENT.

         The obligations of the Guarantors under this Section 4 shall be
automatically reinstated if and to the extent that for any reason any payment by
or on behalf of any Person in respect of the Credit Party Obligations is
rescinded or must be otherwise restored by any holder of any of the Credit Party
Obligations, whether as a result of any proceedings in bankruptcy or
reorganization or otherwise, and each Guarantor agrees that it will indemnify
the Administrative Agent and each Lender on demand for all reasonable costs and
expenses (including, without limitation, reasonable Attorney Costs) incurred by
the Administrative Agent or such Lender in connection with such rescission or
restoration, including any such costs and expenses incurred in defending against
any claim alleging that such payment constituted a preference, fraudulent
transfer or similar payment under any bankruptcy, insolvency or similar law.

         4.6      REMEDIES.

         The Guarantors agree that, as between the Guarantors, on the one hand,
and the Administrative Agent and the Lenders, on the other hand, the Credit
Party Obligations may be declared to be forthwith due and payable as provided in
Section 9 (and shall be deemed to have become automatically due and payable in
the circumstances provided in Section 9) notwithstanding any stay, injunction or
other prohibition preventing such declaration (or preventing such Credit Party
Obligations from becoming automatically due and payable) as against any other
Person and that, in the event of such declaration (or such Credit Party
Obligations being deemed to have become automatically due and payable), such
Credit Party Obligations (whether or not due and payable by any other Person)
shall forthwith become due and payable by the Guarantors.


                                       39
<PAGE>
         4.7      LIMITATION OF GUARANTY.

         Notwithstanding any provision to the contrary contained herein or in
any of the other Credit Documents, to the extent the obligations of any
Guarantor shall be adjudicated to be invalid or unenforceable for any reason
(including, without limitation, because of any applicable state or federal law
relating to fraudulent conveyances or transfers) then the obligations of such
Guarantor hereunder shall be limited to the maximum amount that is permissible
under applicable law (whether federal or state or otherwise and including,
without limitation, the Bankruptcy Code).

         4.8      RIGHTS OF CONTRIBUTION.

         The Credit Parties agree among themselves that, in connection with
payments made hereunder, each Credit Party shall have contribution rights
against the other Credit Parties as permitted under applicable law. Such
contribution rights shall be subordinate and subject in right of payment to the
obligations of the Credit Parties under the Credit Documents and no Credit Party
shall exercise such rights of contribution until all Credit Party Obligations
have been paid in full and the Commitments terminated.

         4.9      RELEASE OF GUARANTORS.

         Subject to Section 7.12(b), if any of the Guarantors shall cease to be
a Material Domestic Subsidiary of the Borrower for any reason subject to and in
accordance with the terms of the Credit Agreement, then such Guarantor shall,
automatically and without any further action on the part of any party to any
Credit Document, and upon notice to the Administrative Agent, be fully released
and discharged from all its liabilities and obligations under or in respect of
the Credit Documents to which such Guarantor is a party (other than liabilities
and obligations resulting from a demand on such Guarantor's Guaranty pursuant to
Section 9.2) and, promptly upon the request of the Borrower and at the expense
of the Borrower, the Administrative Agent shall execute such documents and take
such other action as is reasonably requested by the Borrower to evidence the
release and discharge of such Guarantor from all such liabilities and
obligations and shall, if applicable, certify to the Borrower that such
Guarantor has no liabilities or obligations resulting from a demand on such
Guarantor's Guaranty pursuant to Section 9.2.

                                    SECTION 5

                              CONDITIONS PRECEDENT

         5.1      CLOSING CONDITIONS.

         This Credit Agreement shall become effective upon, and the obligation
of the Lenders to enter into this Credit Agreement is subject to, the receipt by
the Administrative Agent of duly executed copies of this Credit Agreement.

         5.2      CONDITIONS TO INITIAL FUNDING OF THE TERM LOANS.


                                       40
<PAGE>
         The obligation of the Lenders to make the initial Term Loans is subject
to satisfaction (or waiver) of the following conditions:

                  (a)      Credit Documents. Receipt by the Administrative Agent
         of duly executed copies of the Notes requested by the Lenders prior to
         the Funding Date.

                  (b)      Authority Documents. Receipt by the Administrative
         Agent of the following with respect to each Credit Party:

                           (i)      Organizational Documents. Copies of the
                  articles or certificates of incorporation or other
                  organizational documents of each Credit Party certified to be
                  true and complete as of a recent date by the appropriate
                  Governmental Authority of the state or other jurisdiction of
                  its formation and certified by a secretary or assistant
                  secretary of such Credit Party to be true and correct as of
                  the Funding Date.

                           (ii)     Bylaws. A copy of the bylaws or other
                  governing documents of each Credit Party certified by a
                  secretary or assistant secretary of such Credit Party to be
                  true and correct as of the Funding Date.


                           (iii)    Resolutions. Copies of resolutions of the
                  Board of Directors or other governing body of each Credit
                  Party approving and adopting the Credit Documents to which it
                  is a party, the transactions contemplated therein and
                  authorizing execution and delivery thereof, certified by a
                  secretary or assistant secretary of such Credit Party to be
                  true and correct and in full force and effect as of the
                  Funding Date.

                           (iv)     Good Standing. Copies of certificates of
                  good standing, existence or its equivalent with respect to
                  each Credit Party certified as of a recent date in relation to
                  the Funding Date by the appropriate Governmental Authority of
                  the state or other jurisdiction of its formation.

                           (v)      Incumbency. An incumbency certificate of
                  each Credit Party certified by a secretary or assistant
                  secretary of such Credit Party to be true and correct as of
                  the Funding Date.

                  (c)      Opinions of Counsel. Receipt by the Administrative
         Agent of opinions reasonably satisfactory to the Administrative Agent,
         addressed to the Administrative Agent on behalf of the Lenders and
         dated as of the Funding Date.

                  (d)      Consents. Receipt by the Administrative Agent of
         evidence that all necessary governmental, shareholder and material
         third party consents and approvals in connection with the Unilab
         Acquisition and the transactions contemplated hereby (including,
         without limitation, the expiration of the applicable waiting period
         under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as
         amended (or such waiting period is scheduled to expire on the Funding
         Date)) have been received and no condition or Requirement of Law exists
         which would reasonably be likely to restrain, prevent or impose


                                       41
<PAGE>
         any material adverse conditions on the Unilab Acquisition or the
         transactions contemplated hereby.

                  (e)      Officer's Certificates. The Administrative Agent
         shall have received a certificate or certificates executed by an
         Authorized Officer of the Borrower as of the Funding Date stating that
         (i) the financial statements and information delivered to the
         Administrative Agent on or before the Funding Date were prepared in
         good faith and that such financial statements were prepared in
         accordance with GAAP and (ii) immediately after giving effect to this
         Credit Agreement, the other Credit Documents and all the transactions
         contemplated herein or therein to occur on such date, (A) each Credit
         Party is Solvent and the Borrower and its Subsidiaries taken as a whole
         are Solvent, (B) no Default or Event of Default exists, (C) all
         representations and warranties contained herein and in the other Credit
         Documents are true and correct in all material respects, (D) the Credit
         Parties are in compliance with each of the financial covenants set
         forth in Section 7.2 and (E) the Borrower and each of its Material
         Domestic Subsidiaries are in compliance with the terms of all of their
         material debt obligations, including, without limitation, (I) the 2001
         Senior Credit Agreement, (II) the Senior Unsecured Notes and (III) the
         Convertible Notes.

                  (f)      Financial Statements. Receipt by the Administrative
         Agent of any amendment or modification to the pro forma consolidated
         financial statements filed in connection with the S-4, as required by
         the Securities and Exchange Commission, giving effect to the Unilab
         Acquisition.

                  (g)      Material Adverse Effect. Since December 31, 2001
         there shall not have occurred a Material Adverse Effect.

                  (h)      Fees and Expenses. Payment by the Credit Parties of
         all fees (and all expenses for which invoices have been presented at
         least three Business Days prior to the Funding Date) owed by them as of
         the Funding Date to the Agents and the Lenders, including, without
         limitation, as set forth in the Fee Letter.

                  (i)      Unilab Acquisition. The Agreement and Plan of Merger,
         dated April 2, 2002, among the Borrower, Quest Diagnostics Newco
         Incorporated and Unilab remains in full force and effect as of the
         Funding Date.

                  (j)      Joinder Documentation. Receipt by the Administrative
         Agent of Joinder Agreements and such other documentation required by
         Section 7.12(a) with respect to Quest Diagnostics Investments
         Incorporated and Quest Diagnostics Finance Incorporated.

                  (k)      Other. Receipt by the Lenders of such other
         documents, instruments, agreements or information as reasonably and
         timely requested by any Lender through the Administrative Agent.


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<PAGE>
         5.3      CONDITIONS TO ALL EXTENSIONS OF CREDIT.

         In addition to the conditions precedent stated elsewhere herein, the
Lenders shall not be obligated to make Loans unless:

                  (a)      Notice. The Borrower shall have delivered to the
         Administrative Agent, an appropriate Notice of Borrowing, duly executed
         and completed, by the time specified in Section 2.1.

                  (b)      Representations and Warranties. The representations
         and warranties made by the Credit Parties in any Credit Document are
         true and correct in all material respects at and as if made as of such
         date except to the extent they expressly and exclusively relate to an
         earlier date.

                  (c)      No Default. No Default or Event of Default shall
         exist and be continuing either prior to or after giving effect to such
         Loan.

                  (d)      Availability. Immediately after giving effect to the
         making of a Loan (and the application of the proceeds thereof) the sum
         of the outstanding Term Loans shall not exceed the Term Loan Committed
         Amount.

                  (e)      Limits. The number of borrowings under this Credit
         Agreement, after giving effect to the requested Loan, does not exceed
         two (2) and the date of the requested borrowing is on or prior to the
         date that is thirty (30) days after the Funding Date.

The delivery of each Notice of Borrowing shall constitute a representation and
warranty by the Borrower of the correctness of the matters specified in
subsections (b), (c), (d) and (e) above.

                                    SECTION 6

                         REPRESENTATIONS AND WARRANTIES

         The Credit Parties hereby represent to the Administrative Agent and
each Lender that:

         6.1      ORGANIZATION AND GOOD STANDING.

         Each Credit Party (a) is either a partnership, a corporation or a
limited liability company duly organized, validly existing and in good standing
under the laws of the jurisdiction of its organization, (b) is duly qualified
and in good standing as a foreign organization and authorized to do business in
every other jurisdiction where its ownership or operation of property or the
conduct of its business would require it to be qualified, in good standing and
authorized, unless the failure to be so qualified, in good standing or
authorized would not have or would not reasonably be expected to have a Material
Adverse Effect and (c) has the power and authority to own and operate its
properties and to carry on its business as now conducted and as currently
proposed to be conducted.


                                       43
<PAGE>
         6.2      DUE AUTHORIZATION.

         Each Credit Party (a) has the power and authority to execute, deliver
and perform this Credit Agreement and the other Credit Documents to which it is
a party and to incur the obligations herein and therein provided for and (b) has
duly taken all necessary action to authorize, and is duly authorized, to
execute, deliver and perform this Credit Agreement and the other Credit
Documents to which it is a party.

         6.3      ENFORCEABLE OBLIGATIONS.

         Each Credit Party has duly executed this Credit Agreement and each
other Credit Document to which such Credit Party is a party and this Credit
Agreement and such other Credit Documents constitute legal, valid and binding
obligations of such Credit Party enforceable against such Credit Party in
accordance with their respective terms, except as may be limited by bankruptcy
or insolvency laws or similar laws affecting creditors' rights generally or by
general equitable principles.

         6.4      NO CONFLICTS.

         Neither the execution and delivery of the Credit Documents to which it
is a party, nor the consummation of the transactions contemplated herein and
therein, nor the performance of or compliance with the terms and provisions
hereof and thereof by a Credit Party will (a) violate, contravene or conflict
with any provision of such Credit Party's organizational documents, (b) violate,
contravene or conflict with any Requirement of Law (including, without
limitation, Regulations T, U or X), order, writ, judgment, injunction, decree,
license or permit applicable to such Credit Party which violation would have or
would reasonably be expected to have a Material Adverse Effect, (c) violate,
contravene or conflict with contractual provisions of, or cause an event of
default under, any indenture, loan agreement, mortgage, deed of trust, contract
or other agreement or instrument to which such Credit Party is a party or by
which it or its properties may be bound which violation would have or would
reasonably be expected to have a Material Adverse Effect, or (d) result in or
require the creation of any Lien upon or with respect to the properties of such
Credit Party.

         6.5      CONSENTS.

         Except for (a) with respect to the Unilab Acquisition, satisfying the
applicable requirements, if any, of the Securities Act and the Securities
Exchange Act of 1934, as amended, state securities laws or "blue sky laws", the
pre-merger notification requirements of the Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended, and filing and recordation of appropriate
merger documents as required by the Delaware General Corporation Law and (b)
consents, approvals and authorizations which have been obtained or the absence
of which would not have or would not reasonably be expected to have a Material
Adverse Effect, no consent, approval, authorization or order of, or filing,
registration or qualification with, any Governmental Authority, equity owner or
third party in respect of any Credit Party is required in connection with the
execution, delivery or performance of this Credit Agreement or any of the other
Credit Documents, or the consummation of any transaction contemplated herein or
therein by such Credit Party.


                                       44
<PAGE>
         6.6      FINANCIAL CONDITION.

         The financial statements delivered to the Administrative Agent and the
Lenders pursuant to Sections 7.1(a) and (b): (a) have been prepared in
accordance with GAAP and (b) present fairly the consolidated financial
condition, results of operations and cash flows of the Borrower and its
Subsidiaries as of such date and for such periods. Since December 31, 2001,
there has been no sale, transfer or other disposition by the Borrower or any of
its Subsidiaries of any material part of the business or property of the
Borrower and its Subsidiaries, taken as a whole, or purchase or other
acquisition (other than the AML Acquisition and the Unilab Acquisition) by any
such Person of any business or property (including any Capital Stock of any
other Person) material in relation to the consolidated financial condition of
the Borrower and its Subsidiaries, taken as a whole, in each case, which, is not
(i) reflected in the most recent financial statements delivered to the Lenders
prior to the Funding Date or pursuant to Section 7.1 or in the notes thereto or
(ii) otherwise permitted by the terms of this Credit Agreement and communicated
to the Administrative Agent and the Lenders.

         6.7      NO MATERIAL CHANGE.

         Since December 31, 2001, there has been no development or event
relating to or affecting the Borrower or any of its Subsidiaries which has had
or would reasonably be expected to have a Material Adverse Effect.

         6.8      DISCLOSURE.

         Neither this Credit Agreement, nor any other Credit Document, nor any
financial statements delivered to the Administrative Agent or the Lenders nor
any other document, certificate or statement furnished to the Administrative
Agent or the Lenders by or on behalf of any Credit Party in connection with the
transactions contemplated hereby, taken as a whole, contains any untrue
statement of a material fact or omits to state a material fact necessary in
order to make the statements contained therein or herein not misleading.

         6.9      NO DEFAULT.

         No Default or Event of Default has occurred and is continuing or would
result from the consummation of the transactions contemplated by this Credit
Agreement and the other Credit Documents.

         6.10     LITIGATION.

         Except as set forth in Schedule 6.10, no litigation, investigation,
claim, criminal prosecution, civil investigative demand, imposition of criminal
or civil fines and penalties, or any other proceeding of or before any
arbitrator or Governmental Authority is pending or, to the knowledge of the
Borrower, threatened by or against the Borrower or any of its Subsidiaries or
against any of its or their respective Properties (a) with respect to the Credit
Documents or any Loan or any of the transactions contemplated hereby or (b)
which would reasonably be expected to have a Material Adverse Effect.


                                       45
<PAGE>
         6.11     TAXES.

         The Borrower and each of its Subsidiaries has filed, or caused to be
filed, all material tax returns (federal, state, local and foreign) required to
be filed and has paid (a) all amounts of taxes shown thereon to be due
(including interest and penalties) and (b) all other material taxes, fees,
assessments and other governmental charges (including mortgage recording taxes,
documentary stamp taxes and intangibles taxes) owing by it, except for such
taxes (i) which are not yet delinquent or (ii) that are being contested in good
faith and by proper proceedings, and against which adequate reserves are being
maintained in accordance with GAAP.

         6.12     COMPLIANCE WITH LAW.

         Except to the extent the same would not have or would not reasonably be
expected to have a Material Adverse Effect:

                  (a)      The Borrower and each of its Subsidiaries is in
         compliance with all Requirements of Law (including, without limitation,
         Environmental Laws, ERISA, Medicaid Regulations, Medicare Regulations,
         42 U.S.C. (Section) 1320a-7b and 42 U.S.C. (Section) 1395nn) and all
         material orders, writs, injunctions and decrees applicable to it, or to
         its Properties.

                  (b)      (i) Neither the Borrower nor any of its Subsidiaries
         nor any individual employed by the Borrower or any of its Subsidiaries
         who may reasonably be expected to be excluded or suspended from
         participation in any Medical Reimbursement Program for their corporate
         or individual actions or failures to act; and (ii) there is no member
         of management continuing to be employed by the Borrower or any of its
         Subsidiaries who may reasonably be expected to have individual criminal
         culpability for healthcare matters under investigation by any
         Governmental Authority unless such member of management has been,
         within a reasonable period of time after discovery of such actual or
         potential culpability, either suspended or removed from positions of
         responsibility related to those activities under challenge by the
         Governmental Authority.

                  (c)      Current billing policies, arrangements, protocols and
         instructions comply with all material requirements of Medical
         Reimbursement Programs and are administered by properly trained
         personnel.

                  (d)      Current medical director compensation arrangements
         and other arrangements with referring physicians comply with state and
         federal self-referral and anti-kickback laws, including without
         limitation 42 U.S.C. Section 1320a-7b(b)(1) - (b)(2) and 42 U.S.C.
         Section 1395nn.

         6.13     LICENSING AND ACCREDITATION.

         Except to the extent the same would not have or would not be reasonably
expected to have a Material Adverse Effect, each of the Credit Parties has, to
the extent applicable: (a) obtained and maintains in good standing all required
licenses, permits, authorization and


                                       46
<PAGE>
approvals of each Governmental Authority necessary to the conduct of its
business; (b) to the extent prudent and customary in the industry in which it is
engaged, obtained and maintains accreditation from all generally recognized
accrediting agencies (including, but not limited to, CAP); (c) obtained and
maintains CLIA certification; (d) entered into and maintains in good standing
its Medicare Provider Agreements and its Medicaid Provider Agreements; and (e)
ensured that all such required licenses, certifications and accreditations are
in full force and effect on the date hereof and have not been revoked or
suspended or otherwise limited.

         6.14     TITLE TO PROPERTIES, LIENS.

         The Borrower and each of its Subsidiaries, is the owner of, and has
good title to, or has a valid license or lease to use, all of its material
Properties. All Liens on the Properties of the Borrower and its Subsidiaries are
Permitted Liens.

         6.15     INSURANCE.

         The properties of the Borrower and each of its Subsidiaries are insured
with financially sound and reputable insurance companies that are not Affiliates
of the Borrower (except to the extent that self-insurance is maintained in
reasonable amounts), in such amounts, with such deductibles and covering such
risks, as is reasonable and prudent.

         6.16     USE OF PROCEEDS.

         The proceeds of the Loans will be used solely for the purposes
specified in Section 7.10.

         6.17     GOVERNMENT REGULATION.

                  (a)      "Margin stock" within the meaning of Regulation U
         does not constitute more than 25% of the value of the consolidated
         assets of the Borrower and its Subsidiaries. None of the transactions
         contemplated by the Credit Documents (including, without limitation,
         the direct or indirect use of the proceeds of the Loans) will violate
         or result in a violation of (i) the Securities Act, (ii) the Exchange
         Act or (iii) Regulations T, U or X.

                  (b)      Neither the Borrower nor any of its Subsidiaries is
         subject to regulation under the Public Utility Holding Company Act of
         1935, the Federal Power Act or the Investment Company Act of 1940, each
         as amended.

         6.18     ERISA.

         Except as would not result in or would not reasonably be expected to
result in a Material Adverse Effect:

                  (a)      (i) No ERISA Event has occurred, and, to the best
         knowledge of the Borrower, each of its Subsidiaries and each ERISA
         Affiliate, no event or condition has occurred or exists as a result of
         which any ERISA Event could reasonably be expected to


                                       47
<PAGE>
         occur, with respect to any Plan; (ii) no "accumulated funding
         deficiency," as such term is defined in Section 302 of ERISA and
         Section 412 of the Code, whether or not waived, has occurred with
         respect to any Plan and no application for a funding waiver or an
         extension of any amortization period pursuant to Section 412 of the
         Code has been made with respect to any Plan; (iii) each Plan has been
         maintained, operated, and funded in compliance with its own terms and
         in material compliance with the provisions of ERISA, the Code, and any
         other applicable federal or state laws; (iv) each Plan that is intended
         to qualify under Section 401(a) of the Code has received a favorable
         determination letter from the IRS or an application for such a letter
         is currently being processed by the IRS with respect thereto and, to
         the best knowledge of the Borrower, each of its Subsidiaries and each
         ERISA Affiliate, nothing has occurred which would prevent, or cause the
         loss of, such qualification; and (v) no Lien in favor or the PBGC or a
         Plan has arisen or is reasonably likely to arise on account of any
         Plan.

                  (b)      Neither the Borrower nor any Subsidiary of the
         Borrower nor any ERISA Affiliate has incurred, or, to the best of each
         such party's knowledge, is reasonably expected to incur, any liability
         under Title IV of ERISA with respect to any Single Employer Plan, or
         any withdrawal liability under ERISA to any Multiemployer Plan or
         Multiple Employer Plan. Neither the Borrower nor any Subsidiary of the
         Borrower nor any ERISA Affiliate has received any notification that any
         Multiemployer Plan is in reorganization (within the meaning of Section
         4241 of ERISA), is insolvent (within the meaning of Section 4245 of
         ERISA), or has been terminated (within the meaning of Title IV of
         ERISA), and no Multiemployer Plan is, to the best of each such Person's
         knowledge, reasonably expected to be in reorganization, insolvent, or
         terminated. Neither the Borrower nor any Subsidiary of the Borrower nor
         any ERISA Affiliate has engaged in a transaction that could be subject
         to Sections 4069 or 4212(c) of ERISA.

                  (c)      No prohibited transaction (within the meaning of
         Section 406 of ERISA or Section 4975 of the Code) or breach of
         fiduciary responsibility has occurred with respect to a Plan which has
         subjected or may subject the Borrower, any Subsidiary of the Borrower
         or any ERISA Affiliate to any liability under Sections 406, 409,
         502(i), or 502(l) of ERISA or Section 4975 of the Code, or under any
         agreement or other instrument pursuant to which the Borrower, any
         Subsidiary of the Borrower or any ERISA Affiliate has agreed or is
         required to indemnify any person against any such liability. There are
         no pending or, to the best knowledge of the Borrower, each of its
         Subsidiaries and each ERISA Affiliate, threatened claims, actions or
         lawsuits, or action by any Governmental Authority, with respect to any
         Plan that could reasonably be expected to have a Material Adverse
         Effect.

                  (d)      Each Plan that is a welfare plan (as defined in
         Section 3(1) of ERISA) to which Sections 601-609 of ERISA and Section
         4980B of the Code apply has been administered in compliance in all
         material respects with such sections.

         6.19     ENVIRONMENTAL MATTERS.

                  (a)      Except as would not result in or would not reasonably
         be expected to result in a Material Adverse Effect:


                                       48
<PAGE>
                           (i)      Each of the real properties owned, leased or
                  operated by the Borrower or any of its Subsidiaries (the "Real
                  Properties") and all operations at the Real Properties are in
                  compliance with all applicable Environmental Laws, and there
                  is no violation of any Environmental Law with respect to the
                  Real Properties or the businesses operated by the Borrower or
                  any of its Subsidiaries (the "Businesses"), and there are no
                  conditions relating to the Businesses or Real Properties that
                  would reasonably be expected to give rise to liability under
                  any applicable Environmental Laws.

                           (ii)     No Credit Party has received any written
                  notice of, or inquiry from any Governmental Authority
                  regarding, any violation, alleged violation, non-compliance,
                  liability or potential liability regarding Hazardous Materials
                  or compliance with Environmental Laws with regard to any of
                  the Real Properties or the Businesses, nor, to the knowledge
                  of the Borrower or any of its Subsidiaries, is any such notice
                  being threatened.

                           (iii)    Hazardous Materials have not been
                  transported or disposed of from the Real Properties, or
                  generated, treated, stored or disposed of at, on or under any
                  of the Real Properties or any other location, in each case by,
                  or on behalf or with the permission of, the Borrower or any of
                  its Subsidiaries in a manner that would give rise to liability
                  under any applicable Environmental Laws.

                           (iv)     No judicial proceeding or governmental or
                  administrative action is pending or, to the knowledge of the
                  Borrower or any of its Subsidiaries, threatened, under any
                  Environmental Law to which the Borrower or any of its
                  Subsidiaries is or will be named as a party, nor are there any
                  consent decrees or other decrees, consent orders,
                  administrative orders or other orders, or other administrative
                  or judicial requirements outstanding under any Environmental
                  Law with respect to the Borrower or any of its Subsidiaries,
                  the Real Properties or the Businesses.

                           (v)      There has been no release (including,
                  without limitation, disposal) or threat of release of
                  Hazardous Materials at or from the Real Properties, or arising
                  from or related to the operations of the Borrower or any of
                  its Subsidiaries in connection with the Real Properties or
                  otherwise in connection with the Businesses where such release
                  constituted a violation of, or would give rise to liability
                  under, any applicable Environmental Laws.

                           (vi)     None of the Real Properties contains, or has
                  previously contained, any Hazardous Materials at, on or under
                  the Real Properties in amounts or concentrations that, if
                  released, constitute or constituted a violation of, or could
                  give rise to liability under, Environmental Laws.

                           (vii)    Neither the Borrower, nor any of its
                  Subsidiaries, has assumed any liability of any Person (other
                  than among themselves) under any Environmental Law.


                                       49
<PAGE>
                  (b)      The Credit Parties have adopted procedures that are
         designed to (i) ensure that each Credit Party, any of its operations
         and each of the Real Properties complies with applicable Environmental
         Laws and (ii) minimize any liabilities or potential liabilities that
         each Credit Party, any of its operations and each of the Real
         Properties may have under applicable Environmental Laws.

         6.20     INTELLECTUAL PROPERTY.

         The Borrower and each of its Subsidiaries owns, or has the legal right
to use, all material patents, trademarks, tradenames, copyrights, technology,
know-how and processes (the "Intellectual Property") necessary for each of them
to conduct its business as currently conducted other than as would not have or
would not be reasonably expected to have a Material Adverse Effect. No claim has
been asserted and is pending by any Person challenging or questioning the use of
any Intellectual Property owned by the Borrower or any of its Subsidiaries or
that the Borrower or any of its Subsidiaries has a right to use or the validity
or effectiveness of any such Intellectual Property, nor does the Borrower or any
of its Subsidiaries have knowledge of any such claim, and, to the knowledge of
the Borrower and its Subsidiaries, the use of any Intellectual Property by the
Borrower and its Subsidiaries does not infringe on the rights of any Person,
except for such claims and infringements that in the aggregate, would not have
or would not reasonably be expected to have a Material Adverse Effect.

         6.21     SUBSIDIARIES.

         As of the Closing Date, set forth on Schedule 6.21 is a complete and
accurate list of all Subsidiaries of the Borrower and which of such Subsidiaries
are Material Domestic Subsidiaries, in each case after giving effect to the
Unilab Acquisition.

         6.22     SOLVENCY.

         Each Credit Party is and, after consummation of the transactions
contemplated by this Credit Agreement, will be Solvent.

                                    SECTION 7

                              AFFIRMATIVE COVENANTS

         Each Credit Party hereby covenants and agrees that so long as this
Credit Agreement is in effect and until the Loans, together with interest and
fees and other obligations then due and payable hereunder, have been paid in
full and the Commitments hereunder shall have terminated:

         7.1      INFORMATION COVENANTS.

         The Credit Parties will furnish, or cause to be furnished, to the
Administrative Agent and each of the Lenders an electronic (if readily
available) and a hard copy of:


                                       50
<PAGE>
                  (a)      Annual Financial Statements. As soon as available,
         and in any event within 95 days after the close of each fiscal year of
         the Borrower, a consolidated balance sheet and income statement of the
         Borrower and its Subsidiaries, as of the end of such fiscal year,
         together with related consolidated statements of operations, cash flows
         and changes in stockholders' equity for such fiscal year, setting forth
         in comparative form consolidated figures for the preceding fiscal year,
         all such consolidated financial information described above to be
         audited by independent certified public accountants of recognized
         national standing and whose opinion shall be to the effect that such
         financial statements fairly present in all material respects the
         consolidated financial position, results of operations and cash flows
         of the Borrower and its Subsidiaries as at the end of, and for, such
         fiscal year in accordance with GAAP and shall not be limited as to the
         scope of the audit or qualified in any manner.

                  (b)      Quarterly Financial Statements. As soon as available,
         and in any event within 50 days after the close of each of the first
         three fiscal quarters of the Borrower, a consolidated balance sheet and
         income statement of the Borrower and its Subsidiaries, as of the end of
         such fiscal quarter, together with related consolidated statements of
         operations, cash flows and changes in stockholders' equity for such
         fiscal quarter setting forth in each case in comparative form the
         corresponding consolidated statements of operations and cash flows for
         the corresponding period of the preceding fiscal year, and accompanied
         by a certificate of an Authorized Officer of the Borrower to the effect
         that such quarterly financial statements fairly present in all material
         respects the consolidated financial condition of the Borrower and its
         Subsidiaries and in accordance with GAAP, subject to changes resulting
         from audit and normal year-end audit adjustments. Notwithstanding the
         above, it is understood and agreed that delivery of the Borrower's
         applicable Form 10-Q shall satisfy the requirements of this Section
         7.1(b).

                  (c)      Officer's Certificate. At the time of delivery of the
         financial statements provided for in Sections 7.1(a) and 7.1(b) above,
         a certificate of an Authorized Officer of the Borrower substantially in
         the form of Exhibit 7.1(c), (i) demonstrating compliance with the
         financial covenants contained in Section 7.2 and the covenant
         requirements in Sections 7.12(b) and 7.13 by calculation thereof as of
         the end of each such fiscal period, (ii) demonstrating compliance with
         any other terms of this Credit Agreement as reasonably requested by the
         Administrative Agent, (iii) stating that no Default or Event of Default
         exists, or if any Default or Event of Default does exist, specifying
         the nature and extent thereof and what action the Borrower proposes to
         take with respect thereto and (iv) updating Schedule 6.21 as of the end
         of such fiscal period.

                  (d)      Reports. Promptly upon transmission or receipt
         thereof, copies of all financial statements, proxy statements, notices
         and reports as the Borrower or any of its Subsidiaries shall send to
         shareholders of the Borrower generally and, upon request of the
         Administrative Agent, copies of any filings and registrations with, and
         reports to or from, any Governmental Authority which has regulatory
         authority with respect to the Borrower and its Subsidiaries.


                                       51
<PAGE>
                  (e)      Notices. Upon a Credit Party obtaining knowledge
         thereof, the Borrower will give written notice to the Administrative
         Agent promptly (and in any event within five Business Days) of (i) the
         occurrence of an event or condition consisting of a Default or Event of
         Default, specifying the nature and existence thereof and what action
         the Borrower proposes to take with respect thereto, (ii) the occurrence
         of any of the following with respect to the Borrower or any of its
         Subsidiaries (A) the pendency or commencement of any litigation,
         arbitration or governmental proceeding against the Borrower or any of
         its Subsidiaries which (x) would have or would reasonably be expected
         to have a Material Adverse Effect, or (y) would result in a significant
         liability to the Credit Parties or (B) material non-compliance with, or
         the institution of any proceedings against the Borrower or any of its
         Subsidiaries with respect to, or the receipt of written notice by such
         Person of potential liability or responsibility for violation, or
         alleged violation of, any Requirement of Law (including, without
         limitation, Environmental Laws) the violation of which would have or
         would reasonably be expected to have a Material Adverse Effect (iii)
         any change to the Debt Rating of the Borrower, (iv) any investigation
         or proceeding against the Borrower or any of its Subsidiaries to
         suspend, revoke or terminate, any Medicaid Provider Agreement, Medicare
         Provider Agreement, or exclusion from any Medical Reimbursement
         Program, which is reasonably expected to have a Material Adverse
         Effect; and (v) any breach by the Borrower or any of its Subsidiaries
         or any predecessor of the Borrower or any of its Subsidiaries of the
         Corporate Integrity Agreement entered into with the OIG if such breach
         causes the OIG to take any adverse action as a result of such breach.

                  (f)      ERISA. Upon the Borrower, any Subsidiary of the
         Borrower or any ERISA Affiliate obtaining knowledge thereof, such
         Person shall give written notice to the Administrative Agent and each
         of the Lenders promptly (and in any event within two Business Days) of
         the occurrence of any of the following events which has had or would be
         reasonably expected to have a Material Adverse Effect: (i) any
         Reportable Event, that constitutes an ERISA Event; (ii) with respect to
         any Multiemployer Plan, the receipt of notice as prescribed in ERISA or
         otherwise of any withdrawal liability assessed against the Borrower,
         any Subsidiary of the Borrower or any ERISA Affiliate, or of a
         determination that any Multiemployer Plan is in reorganization or
         insolvent (both within the meaning of Title IV of ERISA); (iii) the
         failure to make full payment on or before the due date (including
         extensions) thereof of all amounts which the Borrower, any Subsidiary
         of the Borrower or any ERISA Affiliate is required to contribute to
         each Plan pursuant to its terms and as required to meet the minimum
         funding standard set forth in ERISA and the Code with respect thereto;
         or (iv) any change in the funding status of any Plan that could have a
         Material Adverse Effect; in each case together with a description of
         any such event or condition or a copy of any such notice and a
         statement by an Authorized Officer of the Borrower briefly setting
         forth the details regarding such event, condition, or notice, and the
         action, if any, which has been or is being taken or is proposed to be
         taken by such Person with respect thereto. Promptly upon request, the
         Credit Parties shall furnish the Administrative Agent and the Lenders
         with such additional information concerning any Plan as may be
         reasonably requested, including, but not limited to, copies of each
         annual report/return (Form 5500 series), as well as all schedules and
         attachments thereto required to be filed with the Department of Labor
         and/or the Internal Revenue Service pursuant to


                                       52
<PAGE>
         ERISA and the Code, respectively, for each "plan year" (within the
         meaning of Section 3(39) of ERISA).

                  (g)      Environmental.

                           (i)      Subsequent to a written notice from any
                  Governmental Authority that would reasonably be expected to
                  result in a Material Adverse Effect, or during the existence
                  of an Event of Default, and upon the written request of
                  Administrative Agent, the Credit Parties will furnish or cause
                  to be furnished to the Administrative Agent, at the Credit
                  Parties' expense, a report of an environmental assessment of
                  reasonable scope, form and depth, including, where
                  appropriate, invasive soil or groundwater sampling, by a
                  consultant reasonably acceptable to the Administrative Agent
                  addressing the subject of such notice or, if during the
                  existence of an Event of Default, regarding any release or
                  threat of release of Hazardous Materials on any Property
                  owned, leased or operated by a Credit Party and the compliance
                  by the Credit Parties with Environmental Laws. If the Credit
                  Parties fail to deliver such an environmental report within
                  seventy-five (75) days after receipt of such written request,
                  then the Administrative Agent may arrange for same, and the
                  Credit Parties hereby grant to the Administrative Agent and
                  its representatives access to the Real Properties and a
                  license of a scope reasonably necessary to undertake such an
                  assessment (including, where appropriate, invasive soil or
                  groundwater sampling). The reasonable cost of any assessment
                  arranged for by the Administrative Agent pursuant to this
                  provision will be payable by the Credit Parties on demand.

                           (ii)     Each Credit Party will conduct and complete,
                  or cause to be conducted and completed, all investigations,
                  studies, sampling, and testing and all remedial, removal, and
                  other actions necessary to address all Hazardous Materials on,
                  from, or affecting any Real Properties to the extent necessary
                  to be in compliance with all Environmental Laws and all other
                  applicable federal, state, and local laws, regulations, rules
                  and policies and with the orders and directives of all
                  Governmental Authorities exercising jurisdiction over such
                  Real Properties to the extent any failure would have or would
                  reasonably be expected to have a Material Adverse Effect.

                  (h)      Consummation of the Unilab Acquisition. Upon
         consummation of the Unilab Acquisition, the Borrower will give prompt
         written notice thereof to the Administrative Agent specifying the date
         the Unilab Acquisition was consummated.

                  (i)      Other Information. With reasonable promptness upon
         any such request, such other information regarding the business,
         properties or financial condition of the Borrower and its Subsidiaries
         as the Administrative Agent may reasonably request.

         7.2      FINANCIAL COVENANTS.

                  (a)      Leverage Ratio. The Leverage Ratio, as of the last
         day of each fiscal quarter of the Borrower, shall be less than or equal
         to 3.25 to 1.0.


                                       53
<PAGE>
                  (b)      Fixed Charge Coverage Ratio. The Fixed Charge
         Coverage Ratio, as of the last day of each fiscal quarter of the
         Borrower, shall be greater than or equal to 1.5 to 1.0.

         7.3      PRESERVATION OF EXISTENCE AND FRANCHISES.

         The Borrower will, and will cause its Subsidiaries to, do all things
necessary to preserve and keep in full force and effect its existence, rights,
franchises, Intellectual Property and authority except as permitted by Section
8.4; provided that neither the Borrower nor any of its Subsidiaries shall be
required to preserve any rights, franchises, Intellectual Property or authority
if the Borrower or such Subsidiary shall determine that the preservation thereof
is no longer desirable in the conduct of its business and if the loss thereof
would not have or would not reasonably be expected to have a Material Adverse
Effect.

         7.4      BOOKS AND RECORDS.

         The Borrower will, and will cause its Subsidiaries to, keep complete
and accurate books and records of its transactions in order to produce its
financial statements in accordance with GAAP (including the establishment and
maintenance of appropriate reserves).

         7.5      COMPLIANCE WITH LAW.

         Except to the extent the failure to do so would not have or would not
reasonably be expected to have a Material Adverse Effect, the Borrower will, and
will cause each of its Subsidiaries to, (a) comply with all Requirements of Law,
and all applicable restrictions imposed by all Governmental Authorities,
applicable to it and its Property (including, without limitation, Environmental
Laws and ERISA), (b) conform with and duly observe in all material respects all
laws, rules and regulations and all other valid requirements of any regulatory
authority with respect to the conduct of its business, including without
limitation Titles XVIII and XIX of the Social Security Act, Medicare
Regulations, Medicaid Regulations, and all laws, rules and regulations of
Governmental Authorities, pertaining to the business of the Credit Parties; (c)
obtain and maintain all licenses, permits, certifications and approvals of all
applicable Governmental Authorities as are required for the conduct of its
business as currently conducted and herein contemplated, including without
limitation professional licenses, CLIA certifications, Medicare Provider
Agreements and Medicaid Provider Agreements; and (d) ensure that (i) billing
policies, arrangements, protocols and instructions will comply with
reimbursement requirements under Medicare, Medicaid and other Medical
Reimbursement Programs and will be administered by properly trained personnel;
and (ii) medical director compensation arrangements and other arrangements with
referring physicians will comply with applicable state and federal self-referral
and anti-kickback laws, including without limitation 42 U.S.C. Section
1320a-7b(b)(1) - (b)(2) 42 U.S.C. and 42 U.S.C. Section 1395nn.


                                       54
<PAGE>
         7.6      PAYMENT OF TAXES AND OTHER INDEBTEDNESS.

         The Borrower will, and will cause its Subsidiaries to, pay, settle or
discharge (a) all material taxes, assessments and governmental charges or levies
imposed upon it, or upon its income or profits, or upon any of its properties,
before they shall become delinquent, (b) all material lawful claims (including
claims for labor, materials and supplies) which, if unpaid, might give rise to a
Lien upon any of its properties, and (c) all of its other material Indebtedness
as it shall become due (to the extent such repayment is not otherwise prohibited
by this Credit Agreement); provided, however, that a Credit Party shall not be
required to pay any such tax, assessment, charge, levy, claim or Indebtedness
which is being contested in good faith by appropriate proceedings and as to
which adequate reserves therefor have been established in accordance with GAAP,
unless the failure to make any such payment (i) would give rise to an immediate
right to foreclose or collect on a Lien securing such amounts or (ii) would have
or would reasonably be expected to have a Material Adverse Effect.

         7.7      INSURANCE.

         The Borrower will, and will cause each of its Subsidiaries to, at all
times maintain in full force and effect insurance (including worker's
compensation, liability, casualty and business interruption insurance) with
reputable national companies that are not Affiliates of the Borrower (except to
the extent that self-insurance is maintained in reasonable amounts), in such
amounts, covering such risks and liabilities as is reasonable and prudent.

         7.8      MAINTENANCE OF PROPERTY.

         The Borrower will, and will cause its Subsidiaries to, maintain and
preserve its properties and equipment in good repair, working order and
condition, normal wear and tear excepted, and will make, or cause to be made, in
such properties and equipment from time to time all repairs, renewals,
replacements, extensions, additions, betterments and improvements thereto as may
be needed or proper, in each case to the extent and in the manner customary for
companies in similar businesses.

         7.9      PERFORMANCE OF OBLIGATIONS.

         Except to the extent the failure to do so would not have or would not
reasonably be expected to have a Material Adverse Effect, the Borrower will, and
will cause its Subsidiaries to, perform all of its obligations under the terms
of all contracts, agreements or other agreements not evidencing Indebtedness to
which it is a party or by which it or its Properties may be bound.

         7.10     USE OF PROCEEDS.

         The Borrower will use the proceeds of the Loans solely to (a)
consummate the Unilab Acquisition, (b) repay or pay the purchase price for
Indebtedness of Unilab in connection therewith and (c) pay fees, costs and
expenses incurred in connection with the Unilab Acquisition, including, without
limitation, costs incurred in connection with the tender for the existing high
yield notes of Unilab.


                                       55


<PAGE>
         7.11     AUDITS/INSPECTIONS.

         Upon reasonable notice and during normal business hours, but not more
than once per calendar year, the Borrower will, and will cause each of its
Subsidiaries to, permit representatives appointed by the Administrative Agent or
any Lender, including, without limitation, independent accountants, agents,
attorneys and appraisers to visit and inspect the Borrower's or any Subsidiary's
Property, including its books and records, its accounts receivable and
inventory, its facilities and its other business assets, and to make photocopies
or photographs thereof and to write down and record any information such
representative obtains and shall permit the Administrative Agent, any Lender or
its representatives to investigate and verify the accuracy of information
provided to the Administrative Agent or the Lenders and to discuss all such
matters with the officers, employees and representatives of the Borrower and/or
its Subsidiaries; provided, however, during the existence of a Default or Event
of Default, the Administrative Agent and the Lenders may request as many
inspections as reasonable under the circumstances. Any expenses incurred in
connection with this Section 7.11 shall be for the account of the Lenders unless
an Event of Default exists in which case such expenses shall be for the account
of the Borrower. Any representatives appointed by the Administrative Agent shall
sign a confidentiality agreement reasonably acceptable to the Borrower prior to
any visit, investigation, inspection or verification permitted by this Section
7.11.

         7.12     ADDITIONAL CREDIT PARTIES.

                  (a) At the time any Person becomes a Material Domestic
         Subsidiary or at the time any Subsidiary of the Borrower guaranties the
         2001 Senior Credit Agreement or the Senior Unsecured Notes (if it is
         not already a Guarantor), the Borrower shall so notify the
         Administrative Agent and promptly thereafter (but in any event within
         30 days) shall cause such Person to (i) execute a Joinder Agreement in
         substantially the same form as Exhibit 7.12, and (ii) deliver such
         other documentation as the Administrative Agent may reasonably request
         in connection with the foregoing, including, without limitation,
         certified resolutions and other organizational and authorizing
         documents of such Person and favorable opinions of counsel to such
         Person (which shall cover, among other things, the legality, validity,
         binding effect and enforceability of the documentation referred to
         above), all in form, content and scope reasonably satisfactory to the
         Administrative Agent.

                  (b) If at any time Non-Material Domestic Subsidiaries own
         assets in an aggregate amount greater than five percent (5%) of Total
         Assets or produce revenues in an aggregate amount greater than five
         percent (5%) of the total revenues of the Borrower and its Subsidiaries
         on a consolidated basis, the Borrower will designate one or more
         Non-Material Domestic Subsidiaries to become a Guarantor (and such
         Non-Material Domestic Subsidiary shall become a Guarantor in accordance
         with clause (a) above) so that after giving effect to such designation
         and action, Non-Material Domestic Subsidiaries own assets in the
         aggregate of equal to or less than five percent (5%) of Total Assets
         and produce revenues in an aggregate amount equal to or less than five
         percent (5%) of the total revenues of the Borrower and its Subsidiaries
         on a consolidated basis.


                                       56
<PAGE>
         7.13     CREDIT PARTY REVENUES.

         The Borrower will take such action as is necessary to cause the
aggregate annual net revenues of the Credit Parties, as of the end of each
fiscal quarter for the prior twelve month period, to be greater than or equal to
the lesser of (a) $2,800,000,000 or (b) 80% of the total consolidated annual net
revenues of the Borrower and its Subsidiaries for the prior twelve month period.

         7.14     COMPLIANCE PROGRAM.

         The Borrower will, and will cause each of its Domestic Subsidiaries
that operates a clinical laboratory to, maintain, and be operated in accordance
with, a compliance program which is reasonably designed to provide effective
internal controls that promote adherence to applicable federal and state law and
the program requirements of federal and state health plans, and which includes
the implementation of internal audits and monitoring on a regular basis to
monitor compliance with the requirements of the compliance program and
applicable law, regulations and company policies.

         7.15     UNILAB ACQUISITION.

         The Unilab Acquisition shall, on or before the date 30 days after the
Funding Date, be consummated in accordance with the terms of the execution copy
of the Agreement and Plan of Merger dated as of April 2, 2002 (as such agreement
may be modified (a) with the consent of the Agents and (b) if such modification
would have a material adverse effect on the business, operations or financial
condition of the Borrower, Unilab and their respective Subsidiaries taken as a
whole, with the consent of a majority of the Agents and Co-Documentation Agents,
in each case such consent not to be unreasonably withheld).

                                    SECTION 8

                               NEGATIVE COVENANTS

         Each Credit Party hereby covenants and agrees that so long as this
Credit Agreement is in effect and until the Loans, together with interest, fees
and other obligations then due and payable hereunder, have been paid in full and
the Commitments hereunder shall have terminated:

         8.1      INDEBTEDNESS.

         The Borrower will not permit any of its Subsidiaries to, contract,
create, incur, assume or permit to exist any Indebtedness, other than:

                  (a) Guaranty Obligations arising under this Credit Agreement
         and the other Credit Documents;


                                       57
<PAGE>
                  (b) Indebtedness in respect of current accounts payable and
         accrued expenses incurred in the ordinary course of business;

                  (c) Indebtedness owing by a Subsidiary of the Borrower to the
         Borrower or another Subsidiary of the Borrower;

                  (d) purchase money Indebtedness (including Capital Leases) to
         finance the purchase of fixed assets (including equipment); provided
         that (i) the total of all such Indebtedness shall not exceed an
         aggregate principal amount of $50,000,000 (less any purchase money
         Indebtedness incurred by the Borrower) at any one time outstanding;
         (ii) such Indebtedness when incurred shall not exceed the purchase
         price of the asset(s) financed; and (iii) no such Indebtedness shall be
         refinanced for a principal amount in excess of the principal balance
         outstanding thereon at the time of such refinancing;

                  (e) Indebtedness arising from Permitted Receivables Financings
         in an amount not to exceed $450,000,000, in the aggregate (less any
         Indebtedness incurred by the Borrower arising from Permitted
         Receivables Financings), at any one time outstanding;

                  (f) Indebtedness evidenced by Hedging Agreements entered into
         in the ordinary course of business and not for speculative purposes;

                  (g) any guaranty of Indebtedness of the Borrower;

                  (h) Indebtedness incurred after the Closing Date in connection
         with the acquisition of a Person or Property as long as such
         Indebtedness existed prior to such acquisition and was not created in
         anticipation thereof;

                  (i) Indebtedness existing on the Closing Date as set forth on
         Schedule 8.1; and

                  (j) other unsecured Indebtedness in an amount not to exceed
         $200,000,000, in the aggregate, at any one time outstanding.

         8.2      LIENS.

         The Borrower will not, nor will it permit its Subsidiaries to,
contract, create, incur, assume or permit to exist any Lien with respect to any
of its Property of any kind (whether real or personal, tangible or intangible),
whether now owned or after acquired, other than Permitted Liens.

         8.3      NATURE OF BUSINESS.

         The Borrower will not, nor will it permit its Subsidiaries to, alter
the character of its business from that conducted as of the Closing Date or
engage in any substantial manner in any business other than (a) the business
conducted by the Borrower and its Subsidiaries as of the Closing Date, (b) the
business of MedPlus and its Subsidiaries and (c) other healthcare-related
businesses.


                                       58
<PAGE>
         8.4      CONSOLIDATION AND MERGER.

         The Borrower will not, nor will it permit any Subsidiary to, enter into
any transaction of merger or consolidation or liquidate, wind up or dissolve
itself, or suffer any such liquidation, wind-up or dissolution; provided that
(subject to Sections 7.12 and 7.13) (a) a Subsidiary of the Borrower may merge
into the Borrower or another Subsidiary of the Borrower, (b) a Subsidiary of the
Borrower may merge or consolidate with another Person in a transaction otherwise
permitted by Section 8.5 or (c) the Borrower or a Subsidiary of the Borrower may
merge or consolidate with or into another Person if the following conditions are
satisfied:

                  (i) if such transaction involves total consideration (cash and
         non-cash) in excess of $100,000,000, the Administrative Agent is given
         prior written notice of such action;

                  (ii) if the merger or consolidation involves a Credit Party,
         the surviving entity of such merger or consolidation shall either (A)
         be such Credit Party or (B) be a Subsidiary of the Borrower and
         expressly assume in writing all of the obligations of such Credit Party
         under the Credit Documents; provided that if the transaction is between
         the Borrower and another Person, the Borrower must be the surviving
         entity;

                  (iii) the Credit Parties execute and deliver such documents,
         instruments and certificates as the Administrative Agent may reasonably
         request; and

                  (iv) immediately after giving effect to such transaction, no
         Default or Event of Default shall have occurred and be continuing.

         8.5      SALE OR LEASE OF ASSETS.

         The Borrower will not, nor will it permit its Subsidiaries to, convey,
sell, lease, transfer or otherwise voluntarily dispose of, in one transaction or
a series of transactions, all or any part of its business or assets whether now
owned or hereafter acquired, including, without limitation, inventory,
receivables, equipment, real property interests (whether owned or leasehold) and
securities, other than a sale, lease, transfer or other disposal of (a) subject
to Sections 7.12 and 7.13, assets from the Borrower or one of its Subsidiaries
to each other; (b) inventory and supplies in the ordinary course of business;
(c) obsolete, surplus, slow-moving, idle or worn-out assets no longer used or
useful in the business of such Credit Party or the trade-in of equipment for
equipment in better condition or of better quality; (d) assets which constitute
a Permitted Investment in the ordinary course of business; (e) Receivables
pursuant to a Permitted Receivables Financing; (f) Investments in the Strategic
Investments Portfolio; and (g) assets of the Borrower and its Subsidiaries, in
addition to those permitted above in this Section 8.5; provided that in the case
of this clause (g) (i) no Event of Default exists prior to such transfer, (ii)
no Default or Event of Default exists after giving effect to such transfer and
(iii) after giving effect to such transfer, the aggregate amount of all such
transfers, calculated on a net book value basis, does not exceed ten percent
(10%) of Total Assets, as determined on the last day of the most recently ended
fiscal quarter of the Borrower for which an officer's certificate has been
delivered pursuant to Section 7.1(c).


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<PAGE>
         8.6      INVESTMENTS.

         The Borrower will not, nor will it permit its Subsidiaries to, make or
permit to exist any Investments except for Permitted Investments.

         8.7      TRANSACTIONS WITH AFFILIATES.

         The Borrower will not, nor will it permit its Subsidiaries to, enter
into any transaction or series of transactions, whether or not in the ordinary
course of business, with any officer, director, shareholder, Subsidiary or
Affiliate other than on terms and conditions substantially as favorable as would
be obtainable in a comparable arm's-length transaction with a Person other than
an officer, director, shareholder, Subsidiary or Affiliate, except that,
notwithstanding the foregoing, each of the following shall be permitted: (a)
transactions between or among the Credit Parties; (b) transactions between or
among the Borrower and its wholly owned Subsidiaries as long as such transaction
is not disadvantageous to the Lenders in any material respect; (c) transactions
between or among the Borrower or one or more of its wholly owned Subsidiaries
(on the one hand) and one of the non-wholly owned Subsidiaries of the Borrower
(on the other hand) as long as none of the equity of such non-wholly owned
Subsidiary is owned or controlled by an officer or director of any Credit Party;
(d) advances to employees permitted by clause (f) of the definition of Permitted
Investments; (e) Dividends; (f) fees, compensation and other benefits paid to,
and customary indemnity and reimbursement provided on behalf of, officers,
directors and employees of any Credit Party in the ordinary course of business;
(g) any employment agreements entered into by the Borrower or any of its
Subsidiaries in the ordinary course of business; (h) any Permitted Receivables
Financing; (i) the SBCL Acquisition Agreement and each agreement contemplated
thereunder (including any registration rights agreement or purchase agreement
related thereto) as in effect on June 27, 2001 and (j) transactions and
agreements in existence on the Closing Date and listed on Schedule 8.7 and, in
each case, any amendment thereto, that is not disadvantageous to the Lenders in
any material respect.

         8.8      FISCAL YEAR; ACCOUNTING; ORGANIZATIONAL DOCUMENTS.

         The Borrower will not, nor will it permit its Subsidiaries to, unless
such action would not affect the calculation of the financial covenants in
Section 7.2 or would not or would not reasonably be likely to affect the rights
of the Lenders under the Credit Documents: (a) change its fiscal year other than
changing the fiscal year of a Subsidiary of the Borrower to a calendar year end,
(b) change its accounting procedures, except as a result of changes in GAAP and
in accordance with Section 1.3 or (c) change its organizational or governing
documents.

         8.9      STOCK REPURCHASES.

         The Borrower will not, nor will it permit its Subsidiaries to, directly
or indirectly, purchase, redeem or otherwise acquire or retire or make any
provisions for redemption, acquisition or retirement of any shares of the
Capital Stock of the Borrower of any class or any warrants or options to
purchase any such shares (collectively, a "Stock Repurchase"); provided that the
Borrower or its Subsidiaries may consummate Stock Repurchases (a) in an amount
up to $50,000,000, in the aggregate, during any consecutive period during the
term of this Credit


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Agreement that the Leverage Ratio is greater than or equal to 2.75 to 1.0 and
(b) in an unlimited amount as long as (i) the Leverage Ratio (A) as of the end
of the most recent fiscal quarter of the Borrower for which an officer's
certificate has been delivered pursuant to Section 7.1(c) is less than 2.75 to
1.0 and (B) on a Pro Forma Basis giving effect to such Stock Repurchase, is less
than 2.75 to 1.0, (ii) if (A) the amount of Stock Repurchases during the lesser
of (x) the twelve month period preceding the anticipated Stock Repurchase or (y)
the period from the date of the last certificate delivered pursuant to this
clause (ii) and the date of the anticipated Stock Repurchase plus (B) the amount
of the anticipated Stock Repurchase exceeds, in the aggregate, $100,000,000, the
Borrower shall deliver to the Administrative Agent, prior to making such Stock
Repurchase, a certificate of an Authorized Officer of the Borrower providing
calculations showing that the requirement in clause (b)(i)(B) above is accurate,
(iii) on the date of such Stock Repurchase no Event of Default exists and (iv)
after giving effect to such Stock Repurchase no Default or Event of Default
exists.

         8.10     SALE/LEASEBACKS.

                  (a) Except as set forth in clause (b) below, the Borrower will
         not, and will not permit any Subsidiary to, enter into any Sale and
         Leaseback Transaction with respect to any Principal Property unless:

                           (i) the Sale and Leaseback Transaction is solely with
                  the Borrower or a Guarantor; or

                           (ii) the lease is for a period not in excess of five
                  years, including renewal rights; or

                           (iii) prior to or within 270 days after the
                  completion of the sale of such Principal Property in
                  connection with the Sale and Leaseback Transaction, the
                  Borrower or its Subsidiary applies the net cash proceeds of
                  the sale of such Principal Property to: (A) the prepayment of
                  the Revolving Loans (as defined in the 2001 Senior Credit
                  Agreement) under the 2001 Senior Credit Agreement (with a
                  corresponding permanent reduction in the Revolving Committed
                  Amount (as defined in the 2001 Senior Credit Agreement)) or
                  the prepayment of debt ranking equally with such Revolving
                  Loans; or (B) the acquisition of different property,
                  facilities or equipment or the expansion of the Borrower and
                  its Subsidiaries' existing business, including the acquisition
                  of other businesses.

                  (b) In addition to the Sale and Leaseback Transactions
         permitted by clause (a) above, the Borrower or any of its Subsidiaries
         may enter into any Sale and Leaseback Transactions if all Attributable
         Debt (measured, in each case, at the time such Sale and Leaseback
         Transaction is entered into by the Borrower or its Subsidiary) in
         respect of such Sale and Leaseback Transactions (not including any Sale
         and Leaseback Transactions permitted under clause (a) above), in the
         aggregate, does not exceed 5% of Total Assets.


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                                    SECTION 9

                                EVENTS OF DEFAULT

         9.1      EVENTS OF DEFAULT.

         An Event of Default shall exist upon the occurrence, and during the
continuation, of any of the following specified events (each an "Event of
Default"):

                  (a) Payment. Any Credit Party shall default in the payment (i)
         when due of any principal of any of the Loans or (ii) within three
         Business Days of when due of any interest on the Loans or any fees or
         other amounts owing hereunder, under any of the other Credit Documents
         or in connection herewith.

                  (b) Representations. Any representation, warranty or statement
         made or deemed to be made by any Credit Party herein, in any of the
         other Credit Documents, or in any statement or certificate delivered or
         required to be delivered pursuant hereto or thereto shall prove untrue
         in any material respect on the date as of which it was made or deemed
         to have been made.

                  (c)      Covenants.  Any Credit Party shall:

                           (i) default in the due performance or observance of
                  any term, covenant or agreement contained in Sections 7.2,
                  7.3, 7.10, 7.12, 7.13 or 7.15 or Section 8 inclusive;

                           (ii) default in the due performance or observance by
                  it of any term, covenant or agreement contained in Section 7.1
                  (excepting Section 7.1(e) for which the unremedied period
                  shall only be five Business Days) and 7.11 and such default
                  shall continue unremedied for a period of ten Business Days;
                  or

                           (iii) default in the due performance or observance by
                  it of any term, covenant or agreement (other than those
                  referred to in subsections (a), (b) or (c)(i) or (ii) of this
                  Section 9.1) contained in this Credit Agreement and such
                  default shall continue unremedied for a period of at least 30
                  days after the earlier of an Authorized Officer of the
                  Borrower becoming aware of such default or notice thereof
                  given by the Administrative Agent.

                  (d) Other Credit Documents. (i) Any Credit Party shall default
         in the due performance or observance of any term, covenant or agreement
         in any of the other Credit Documents and such default shall continue
         unremedied for a period of at least 30 days after the earlier of an
         Authorized Officer of the Borrower becoming aware of such default or
         notice thereof given by the Administrative Agent, (ii) any Credit
         Document shall fail to be in full force and effect or any Credit Party
         shall so assert or (iii) any Credit Document shall fail to give the
         Administrative Agent and/or the Lenders the rights, powers and
         privileges purported to be created by such Credit Document.


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<PAGE>
                  (e) Guaranties. The guaranty given by the Credit Parties
         hereunder or by any Additional Credit Party or material provision
         thereof shall cease to be in full force and effect, or any Guarantor or
         any Person acting by or on behalf of such Guarantor shall deny or
         disaffirm such Guarantor's obligations under such guaranty or such
         Guarantor shall default in the due payment or performance of such
         guaranty.

                  (f) Bankruptcy, etc. The occurrence of any of the following
         with respect to a Credit Party (i) a court or governmental agency
         having jurisdiction in the premises shall enter a decree or order for
         relief in respect of a Credit Party in an involuntary case under any
         applicable bankruptcy, insolvency or other similar law now or hereafter
         in effect, or appoint a receiver, liquidator, assignee, custodian,
         trustee, sequestrator, administrator or similar official of a Credit
         Party or for any substantial part of its Property or ordering the
         winding up or liquidation of, or an administrator in respect of, its
         affairs; or (ii) an involuntary case under any applicable bankruptcy,
         insolvency or other similar law now or hereafter in effect is commenced
         against a Credit Party and such petition remains unstayed and in effect
         for a period of 60 consecutive days; or (iii) a Credit Party shall
         commence a voluntary case under any applicable bankruptcy, insolvency
         or other similar law now or hereafter in effect, or consent to the
         entry of an order for relief in an involuntary case under any such law,
         or consent to the appointment or taking possession by a receiver,
         liquidator, assignee, custodian, trustee, sequestrator, administrator
         or similar official of such Person or any substantial part of its
         Property or make any general assignment for the benefit of creditors;
         or (iv) a Credit Party shall fail generally, or shall admit in writing
         its inability, to pay its debts as they become due or any action shall
         be taken by such Person in furtherance of any of the aforesaid
         purposes.

                  (g) Defaults under Other Indebtedness. With respect to any
         Indebtedness in excess of $50,000,000 (other than Indebtedness
         outstanding under this Credit Agreement) of the Borrower or any of its
         Subsidiaries (A) such Person shall (x) default in any payment (beyond
         the applicable grace period with respect thereto, if any) with respect
         to any such Indebtedness, or (y) default (after giving effect to any
         applicable grace period) in the observance or performance relating to
         such Indebtedness or contained in any instrument or agreement
         evidencing, securing or relating thereto, or any other event or
         condition shall occur or condition exist, the effect of which default
         or other event or condition is to cause, or permit, the holder or
         holders of such Indebtedness (or trustee or agent on behalf of such
         holders, if any) to require (determined without regard to whether any
         notice or lapse of time is required) any such Indebtedness to become
         due prior to its stated maturity; or (B) any such Indebtedness shall be
         declared due and payable, or required to be prepaid other than by a
         regularly scheduled required prepayment prior to the stated maturity
         thereof; or (C) any such Indebtedness shall mature and remain unpaid.

                  (h) Judgments. One or more judgments, orders, or decrees shall
         be entered against any one or more of the Borrower and its Subsidiaries
         involving a liability of $50,000,000 or more, in the aggregate, (to the
         extent not paid, covered by insurance provided by a carrier who has
         acknowledged coverage or covered by an indemnification from Corning
         Incorporated or SmithKline Beecham PLC) and such judgments, orders or



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         decrees (i) are the subject of any enforcement proceeding commenced by
         any creditor or (ii) shall continue unsatisfied, undischarged and
         unstayed for a period ending on the first to occur of (A) the last day
         on which such judgment, order or decree becomes final and unappealable
         or (B) 60 days.

                  (i) ERISA. The occurrence of any of the following events or
         conditions which individually or in the aggregate has had or would
         reasonably be expected to have a Material Adverse Effect: (i) any
         "accumulated funding deficiency," as such term is defined in Section
         302 of ERISA and Section 412 of the Code, whether or not waived, shall
         exist with respect to any Plan, other than a Multiemployer Plan, or any
         Lien shall arise on the assets of the Borrower, any Subsidiary of the
         Borrower or any ERISA Affiliate in favor of the PBGC or a Plan, other
         than a Multiemployer Plan; (ii) an ERISA Event shall occur with respect
         to a Single Employer Plan, which is reasonably likely to result in the
         termination of such Plan for purposes of Title IV of ERISA; (iii) an
         ERISA Event shall occur with respect to a Multiemployer Plan or
         Multiple Employer Plan, which is reasonably likely to result in (A) the
         termination of such plan for purposes of Title IV of ERISA, or (B) the
         Borrower, any Subsidiary of the Borrower or any ERISA Affiliate
         incurring any liability in connection with a withdrawal from,
         reorganization of (within the meaning of Section 4241 of ERISA), or
         insolvency (within the meaning of Section 4245 of ERISA) of such plan;
         (iv) any prohibited transaction (within the meaning of Section 406 of
         ERISA or Section 4975 of the Code) or breach of fiduciary
         responsibility shall occur which may subject the Borrower, any
         Subsidiary of the Borrower or any ERISA Affiliate to any liability
         under Sections 406, 409, 502(i), or 502(l) of ERISA or Section 4975 of
         the Code, or under any agreement or other instrument pursuant to which
         the Borrower, any Subsidiary of the Borrower or any ERISA Affiliate has
         agreed or is required to indemnify any Person against any such
         liability; or (v) the Borrower, any Subsidiary of the Borrower or any
         ERISA Affiliate fails to pay when due, after the expiration of any
         applicable grace period, any installment payment with respect to its
         withdrawal liability under Section 4201 of ERISA under a Multiemployer
         Plan in an aggregate amount in excess of $50,000,000.

                  (j) Ownership. There shall occur a Change of Control.

                  (k) Cross Default. There shall occur an Event of Default (as
         defined in the 2001 Senior Credit Agreement to the extent the 2001
         Senior Credit Agreement has not been terminated).

         9.2      ACCELERATION; REMEDIES.

         Upon the occurrence and during the continuation of an Event of Default,
the Administrative Agent may or shall, upon the request and direction of the
Required Lenders, take the following actions without prejudice to the rights of
the Administrative Agent or any Lender to enforce its claims against the Credit
Parties, except as otherwise specifically provided for herein:

                  (a) Termination of Commitments. Declare the Commitments
         terminated whereupon the Commitments shall be immediately terminated.


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<PAGE>
                  (b) Acceleration of Loans. Declare the unpaid principal of and
         any accrued interest in respect of all Loans and any and all other
         Indebtedness or obligations of any and every kind owing by a Credit
         Party to any of the Lenders under the Credit Documents to be due
         whereupon the same shall be immediately due and payable without
         presentment, demand, protest or other notice of any kind, all of which
         are hereby waived by the Credit Parties.

                  (c) Enforcement of Rights. To the extent permitted by law,
         enforce any and all rights and interests created and existing under the
         Credit Documents, including, without limitation, all rights and
         remedies against a Guarantor and all rights of set-off.

Notwithstanding the foregoing, if an Event of Default specified in Section
9.1(f) shall occur, then the Commitments shall automatically terminate and all
Loans, all accrued interest in respect thereof, all accrued and unpaid fees and
other indebtedness or obligations owing to the Lenders hereunder shall
immediately become due and payable without the giving of any notice or other
action by the Administrative Agent or the Lenders, which notice or other action
is expressly waived by the Credit Parties.

Notwithstanding the fact that enforcement powers reside primarily with the
Administrative Agent, each Lender has, to the extent permitted by law, a
separate right of payment and shall be considered a separate "creditor" holding
a separate "claim" within the meaning of Section 101(5) of the Bankruptcy Code
or any other insolvency statute.

         9.3      ALLOCATION OF PAYMENTS AFTER EVENT OF DEFAULT.

         Notwithstanding any other provisions of this Credit Agreement, after
the occurrence and during the continuation of an Event of Default, all amounts
collected or received by the Administrative Agent or any Lender on account of
amounts outstanding under any of the Credit Documents shall be paid over or
delivered as follows:

                  FIRST, to the payment of all reasonable out-of-pocket costs
         and expenses (including without limitation reasonable Attorney Costs)
         of the Administrative Agent or any of the Lenders in connection with
         enforcing the rights of the Lenders under the Credit Documents, pro
         rata as set forth below;

                  SECOND, to payment of any fees owed to the Administrative
         Agent or any Lender, pro rata as set forth below;

                  THIRD, to the payment of all accrued interest payable to the
         Lenders hereunder, pro rata as set forth below;

                  FOURTH, to the payment of the outstanding principal amount of
         the Loans, pro rata as set forth below;


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<PAGE>
                  FIFTH, to all other obligations which shall have become due
         and payable under the Credit Documents and not repaid pursuant to
         clauses "FIRST" through "FOURTH" above; and

                  SIXTH, to the payment of the surplus, if any, to whoever may
         be lawfully entitled to receive such surplus.

In carrying out the foregoing, (a) amounts received shall be applied in the
numerical order provided until exhausted prior to application to the next
succeeding category; and (b) each of the Lenders shall receive an amount equal
to its pro rata share (based on the proportion that the then outstanding Loans
held by such Lender bears to the aggregate then outstanding Loans) of amounts
available to be applied.

                                   SECTION 10

                                AGENCY PROVISIONS

         10.1     APPOINTMENT.

                  (a) Each Lender hereby irrevocably appoints, designates and
         authorizes the Administrative Agent to take such action on its behalf
         under the provisions of this Credit Agreement and each other Credit
         Document and to exercise such powers and perform such duties as are
         expressly delegated to it by the terms of this Credit Agreement or any
         other Credit Document, together with such powers as are reasonably
         incidental thereto. Notwithstanding any provision to the contrary
         contained elsewhere herein or in any other Credit Document, the
         Administrative Agent shall not have any duties or responsibilities,
         except those expressly set forth herein, nor shall the Administrative
         Agent have or be deemed to have any fiduciary or trustee relationship
         with any Lender or participant, and no implied covenants, functions,
         responsibilities, duties, obligations or liabilities shall be read into
         this Credit Agreement or any other Credit Document or otherwise exist
         against the Administrative Agent. Without limiting the generality of
         the foregoing sentence, the use of the term "agent" herein and in the
         other Credit Documents with reference to the Administrative Agent is
         not intended to connote any fiduciary or other implied (or express)
         obligations arising under agency doctrine of any applicable law.
         Instead, such term is used merely as a matter of market custom, and is
         intended to create or reflect only an administrative relationship
         between independent contracting parties.

                  (b) Each of (i) Merrill Lynch & Co., Merrill Lynch, Pierce,
         Fenner & Smith Incorporated in its capacity as Syndication Agent and
         (ii) Wachovia Bank, National Association, Deutsche Bank Securities Inc.
         and The Bank of New York in their capacity as Co-Documentation Agents,
         shall have no duties or obligations whatsoever under this Credit
         Agreement or the other Credit Documents.


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<PAGE>
         10.2     DELEGATION OF DUTIES.

         The Administrative Agent may execute any of its duties under this
Credit Agreement or any other Credit Document by or through agents, employees or
attorneys-in-fact and shall be entitled to advice of counsel and other
consultants or experts concerning all matters pertaining to such duties. The
Administrative Agent shall not be responsible for the negligence or misconduct
of any agent or attorney-in-fact that it selects with reasonable care.

         10.3     EXCULPATORY PROVISIONS.

         No Agent-Related Person shall (a) be liable for any action taken or
omitted to be taken by any of them under or in connection with this Credit
Agreement or any other Credit Document or the transactions contemplated hereby
(except for its own gross negligence or willful misconduct in connection with
its duties expressly set forth herein), or (b) be responsible in any manner to
any Lender or participant for any recital, statement, representation or warranty
made by any Credit Party or any officer thereof, contained herein or in any
other Credit Document, or in any certificate, report, statement or other
document referred to or provided for in, or received by the Administrative Agent
under or in connection with, this Credit Agreement or any other Credit Document,
or the validity, effectiveness, genuineness, enforceability or sufficiency of
this Credit Agreement or any other Credit Document, or for any failure of any
Credit Party or any other party to any Credit Document to perform its
obligations hereunder or thereunder. No Agent-Related Person shall be under any
obligation to any Lender or participant to ascertain or to inquire as to the
observance or performance of any of the agreements contained in, or conditions
of, this Credit Agreement or any other Credit Document, or to inspect the
properties, books or records of any Credit Party or any Affiliate thereof.

         10.4     RELIANCE ON COMMUNICATIONS.

                  (a) The Administrative Agent shall be entitled to rely, and
         shall be fully protected in relying, upon any writing, communication,
         signature, resolution, representation, notice, consent, certificate,
         affidavit, letter, telegram, facsimile, telex or telephone message,
         statement or other document or conversation believed by it to be
         genuine and correct and to have been signed, sent or made by the proper
         Person or Persons, and upon advice and statements of legal counsel
         (including counsel to any Credit Party), independent accountants and
         other experts selected by the Administrative Agent. The Administrative
         Agent may deem and treat each Lender as the owner of its interests
         hereunder for all purposes unless a written notice of assignment,
         negotiation or transfer thereof shall have been delivered to the
         Administrative Agent in accordance with Section 11.3(b). The
         Administrative Agent shall be fully justified in failing or refusing to
         take any action under any Credit Document unless it shall first receive
         such advice or concurrence of the Required Lenders as it deems
         appropriate and, if it so requests, it shall first be indemnified to
         its satisfaction by the Lenders against any and all liability and
         expense which may be incurred by it by reason of taking or continuing
         to take any such action. The Administrative Agent shall in all cases be
         fully protected in acting, or in refraining from acting, under this
         Credit Agreement or any other Credit Document in accordance with a
         request or consent of the Required Lenders or all the Lenders, if


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<PAGE>
         required hereunder, and such request and any action taken or failure to
         act pursuant thereto shall be binding upon all the Lenders and
         participants, and their respective successors and assigns. Where this
         Credit Agreement expressly permits or prohibits an action unless the
         Required Lenders otherwise determine, the Administrative Agent shall,
         and in all other instances, the Administrative Agent may, but shall not
         be required to, initiate any solicitation for the consent or a vote of
         the Lenders.

                  (b) For purposes of determining compliance with the conditions
         specified in Section 5.1, each Lender that has signed this Credit
         Agreement shall be deemed to have consented to, approved or accepted or
         to be satisfied with, each document or other matter either sent by the
         Administrative Agent to such Lender for consent, approval, acceptance
         or satisfaction, or required thereunder to be consented to or approved
         by or acceptable or satisfactory to a Lender.

         10.5     NOTICE OF DEFAULT.

         The Administrative Agent shall not be deemed to have knowledge or
notice of the occurrence of any Default or Event of Default, except with respect
to defaults in the payment of principal, interest and fees required to be paid
to the Administrative Agent for the account of the Lenders, unless the
Administrative Agent shall have received written notice from a Lender or the
Borrower referring to this Credit Agreement, describing such Default or Event of
Default and stating that such notice is a "notice of default." The
Administrative Agent will notify the Lenders of its receipt of any such notice.
The Administrative Agent shall take such action with respect to such Default or
Event of Default as may be reasonably directed by the Required Lenders in
accordance with Section 9.2; provided, however, that unless and until the
Administrative Agent has received any such direction, the Administrative Agent
may (but shall not be obligated to) take such action, or refrain from taking
such action, with respect to such Default or Event of Default as it shall deem
advisable or in the best interest of the Lenders.

         10.6     NON-RELIANCE ON ADMINISTRATIVE AGENT AND OTHER LENDERS.

         Each Lender acknowledges that no Agent-Related Person has made any
representation or warranty to it, and that no act by the Administrative Agent
hereinafter taken, including any consent to and acceptance of any assignment or
review of the affairs of any Credit Party or any Affiliate thereof, shall be
deemed to constitute any representation or warranty by any Agent-Related Person
to any Lender as to any matter, including whether Agent-Related Persons have
disclosed material information in their possession. Each Lender represents to
the Administrative Agent that it has, independently and without reliance upon
any Agent-Related Person or any other Lender and based on such documents and
information as it has deemed appropriate, made its own appraisal of and
investigation into the business, prospects, operations, Property, financial and
other condition and creditworthiness of the Credit Parties and their respective
Affiliates, and all applicable bank or other regulatory laws relating to the
transactions contemplated hereby, and made its own decision to enter into this
Credit Agreement and to extend credit to the Borrower hereunder. Each Lender
also represents that it will, independently and without reliance upon any
Agent-Related Person or any other Lender and based on such documents and
information as it shall deem appropriate at the time, continue to make its own
credit analysis, appraisals and


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<PAGE>
decisions in taking or not taking action under this Credit Agreement and the
other Credit Documents, and to make such investigations as it deems necessary to
inform itself as to the business, prospects, operations, Property, financial and
other condition and creditworthiness of the Borrower. Except for notices,
reports and other documents expressly required to be furnished to the Lenders by
the Administrative Agent herein, the Administrative Agent shall not have any
duty or responsibility to provide any Lender with any credit or other
information concerning the business, prospects, operations, Property, financial
and other condition or creditworthiness of any of the Credit Parties or any of
their respective Affiliates which may come into the possession of any
Agent-Related Person.

         10.7     INDEMNIFICATION.

         Whether or not the transactions contemplated hereby are consummated,
the Lenders shall indemnify upon demand each Agent-Related Person (to the extent
not reimbursed by or on behalf of any Credit Party and without limiting the
obligation of any Credit Party to do so), pro rata, and hold harmless each
Agent-Related Person from and against any and all Indemnified Liabilities
incurred by it; provided, however, that no Lender shall be liable for the
payment to any Agent-Related Person of any portion of such Indemnified
Liabilities resulting from such Agent-Related Person's gross negligence or
willful misconduct; it being understood that no action taken in accordance with
the directions of the Required Lenders shall be deemed to constitute gross
negligence or willful misconduct for purposes of this Section 10.7. Without
limitation of the foregoing, each Lender shall reimburse the Administrative
Agent upon demand for its ratable share of any costs or out-of-pocket expenses
(including Attorney Costs) incurred by the Administrative Agent in connection
with the preparation, execution, delivery, administration, modification,
amendment or enforcement (whether through negotiations, legal proceedings or
otherwise) of, or legal advice in respect of rights or responsibilities under,
this Credit Agreement, any other Credit Document, or any document contemplated
by or referred to herein, to the extent that the Administrative Agent is not
reimbursed for such expenses by or on behalf of the Credit Parties. The
undertaking in this Section 10.7 shall survive termination of the Commitments,
the payment of all Obligations hereunder and the resignation or replacement of
the Administrative Agent.

         10.8     ADMINISTRATIVE AGENT IN ITS INDIVIDUAL CAPACITY.

         Bank of America and its Affiliates may make loans to, issue letters of
credit for the account of, accept deposits from, acquire equity interests in and
generally engage in any kind of banking, trust, financial advisory, underwriting
or other business with each of the Credit Parties and their respective
Affiliates as though Bank of America were not the Administrative Agent hereunder
and without notice to or consent of the Lenders. The Lenders acknowledge that,
pursuant to such activities, Bank of America or its Affiliates may receive
information regarding any Credit Party or its Affiliates (including information
that may be subject to confidentiality obligations in favor of such Credit Party
or such Affiliate) and that the Administrative Agent shall be under no
obligation to provide such information to them. With respect to its Loans, Bank
of America shall have the same rights and powers under this Credit Agreement as
any other Lender and may exercise such rights and powers as though it were not
the Administrative Agent, and the terms "Lender" and "Lenders" include Bank of
America in its individual capacity.


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<PAGE>
         10.9     SUCCESSOR AGENT.

         The Administrative Agent may resign as Administrative Agent upon 30
days' notice to the Lenders. If the Administrative Agent resigns under this
Credit Agreement, the Required Lenders shall appoint from among the Lenders a
successor administrative agent for the Lenders which successor administrative
agent (such appointment, absent the existence of an Event of Default, to be
subject to the consent of the Borrower, which consent of the Borrower shall not
be unreasonably withheld or delayed). If no successor administrative agent is
appointed prior to the effective date of the resignation of the Administrative
Agent, the Administrative Agent may appoint, after consulting with the Lenders
and the Borrower, a successor administrative agent from among the Lenders. Upon
the acceptance of its appointment as successor administrative agent hereunder,
such successor administrative agent shall succeed to all the rights, powers and
duties of the retiring Administrative Agent and the term "Administrative Agent"
shall mean such successor administrative agent and the retiring Administrative
Agent's appointment, powers and duties as Administrative Agent shall be
terminated. After any retiring Administrative Agent's resignation hereunder as
Administrative Agent, the provisions of this Section 10 and Sections 11.5 and
11.10 shall continue to inure to its benefit as to any actions taken or omitted
to be taken by it while it was Administrative Agent under this Credit Agreement.
If no successor administrative agent has accepted appointment as Administrative
Agent by the date which is 30 days following a retiring Administrative Agent's
notice of resignation, the retiring Administrative Agent's resignation shall
nevertheless thereupon become effective and the Lenders shall perform all of the
duties of the Administrative Agent hereunder until such time, if any, as the
Required Lenders appoint a successor agent as provided for above.

                                   SECTION 11

                                  MISCELLANEOUS

         11.1     NOTICES.

         Except as otherwise expressly provided herein, all notices and other
communications shall have been duly given and shall be effective (a) when
delivered, (b) when transmitted via telecopy (or other facsimile device) to the
number set forth on Schedule 11.1, (c) the Business Day following the day on
which the same has been delivered prepaid (or subject to an invoice arrangement)
to a reputable national overnight air courier service, or (d) the third Business
Day following the day on which the same is sent by certified or registered mail,
postage prepaid, in each case to the respective parties at the address or
telecopy numbers set forth on Schedule 11.1, or at such other address as such
party may specify by written notice to the other parties hereto.

         11.2     RIGHT OF SET-OFF.

                  In addition to any rights now or hereafter granted under
         applicable law or otherwise, and not by way of limitation of any such
         rights, upon the occurrence of an Event of Default and the commencement
         of remedies described in Section 9.2, each Lender is authorized at


                                       70
<PAGE>
         any time and from time to time, without presentment, demand, protest or
         other notice of any kind (all of which rights being hereby expressly
         waived), to set-off and to appropriate and apply any and all deposits
         (general or special) and any other indebtedness at any time held or
         owing by such Lender (including, without limitation, branches, agencies
         or Affiliates of such Lender wherever located) to or for the credit or
         the account of any Credit Party against obligations and liabilities of
         such Credit Party to the Lenders hereunder, under the Notes, the other
         Credit Documents or otherwise, irrespective of whether the
         Administrative Agent or the Lenders shall have made any demand
         hereunder and although such obligations, liabilities or claims, or any
         of them, may be contingent or unmatured, and any such set-off shall be
         deemed to have been made immediately upon the occurrence of an Event of
         Default even though such charge is made or entered on the books of such
         Lender subsequent thereto. The Credit Parties hereby agree that any
         Person purchasing a participation in the Loans and Commitments
         hereunder pursuant to Sections 11.3(e) or 3.8 may exercise all rights
         of set-off with respect to its participation interest as fully as if
         such Person were a Lender hereunder.

         11.3     BENEFIT OF AGREEMENT.

                  (a) Generally. This Credit Agreement shall be binding upon and
         inure to the benefit of and be enforceable by the respective successors
         and assigns of the parties hereto; provided that none of the Credit
         Parties may assign and transfer any of its interests (except as
         permitted by Section 8.4 or 8.5) without the prior written consent of
         the Lenders; and provided further that the rights of each Lender to
         transfer, assign or grant participations in its rights and/or
         obligations hereunder shall be limited as set forth below in this
         Section 11.3.

                  (b) Assignments. Each Lender may assign to one or more
         Eligible Assignees all or a portion of its rights and obligations under
         this Credit Agreement (including, without limitation, all or a portion
         of its Loans, its Note and its Commitment); provided, however, that:

                           (i) each such assignment shall be to an Eligible
                  Assignee;

                           (ii) except (A) in the case of an assignment to
                  another Lender, (B) in the case of an assignment of all of a
                  Lender's rights and obligations under this Credit Agreement,
                  or (C) with the consent of the Administrative Agent and the
                  Borrower, any such partial assignment shall be in an amount at
                  least equal to $5,000,000 (or, if less, the remaining amount
                  of the outstanding Commitment and/or outstanding Term Loans,
                  as applicable, of such assigning Lender) or an integral
                  multiple of $500,000 in excess thereof;

                           (iii) each such assignment by a Lender shall be of a
                  constant, and not varying, percentage of all of its rights and
                  obligations under this Credit Agreement and the Notes;

                           (iv) the parties to such assignment shall execute and
                  deliver to the Administrative Agent for its acceptance an
                  Assignment Agreement in


                                       71
<PAGE>
                  substantially the form of Exhibit 11.3(b), together with a
                  processing fee from the assignor of $3,500; provided, however,
                  no such fee shall be payable in the case of an assignment from
                  a Lender to an Approved Fund; and

                           (v) no such assignment shall be permitted prior to
                  the Funding Date.

         Upon execution, delivery, and acceptance of such Assignment Agreement,
         the assignee thereunder shall be a party hereto and, to the extent of
         such assignment, have the obligations, rights, and benefits of a Lender
         hereunder and the assigning Lender shall, to the extent of such
         assignment, relinquish its rights and be released from its obligations
         under this Credit Agreement. Upon the consummation of any assignment
         pursuant to this Section 11.3(b), the assignor, the Administrative
         Agent and the Borrower shall make appropriate arrangements so that, if
         required or requested, new Notes are issued to the assignor and the
         assignee. If the assignee is a foreign corporation, foreign partnership
         or foreign trust within the meaning of the Code, it shall deliver to
         the Borrower and the Administrative Agent certification as to exemption
         from deduction or withholding of taxes in accordance with Section 3.13.

         By executing and delivering an assignment agreement in accordance with
         this Section 11.3(b), the assigning Lender thereunder and the assignee
         thereunder shall be deemed to confirm to and agree with each other and
         the other parties hereto as follows: (A) such assigning Lender warrants
         that it is the legal and beneficial owner of the interest being
         assigned thereby free and clear of any adverse claim and the assignee
         warrants that it is an Eligible Assignee; (B) except as set forth in
         clause (A) above, such assigning Lender makes no representation or
         warranty and assumes no responsibility with respect to any statements,
         warranties or representations made in or in connection with this Credit
         Agreement, any of the other Credit Documents or any other instrument or
         document furnished pursuant hereto or thereto, or the execution,
         legality, validity, enforceability, genuineness, sufficiency or value
         of this Credit Agreement, any of the other Credit Documents or any
         other instrument or document furnished pursuant hereto or thereto or
         the financial condition of any Credit Party or the performance or
         observance by any Credit Party of any of its obligations under this
         Credit Agreement, any of the other Credit Documents or any other
         instrument or document furnished pursuant hereto or thereto; (C) such
         assignee represents and warrants that it is legally authorized to enter
         into such assignment agreement; (D) such assignee confirms that it has
         received a copy of this Credit Agreement, the other Credit Documents
         and such other documents and information as it has deemed appropriate
         to make its own credit analysis and decision to enter into such
         assignment agreement; (E) such assignee will independently and without
         reliance upon the Administrative Agent, such assigning Lender or any
         other Lender, and based on such documents and information as it shall
         deem appropriate at the time, continue to make its own credit decisions
         in taking or not taking action under this Credit Agreement and the
         other Credit Documents; (F) such assignee appoints and authorizes the
         Administrative Agent to take such action on its behalf and to exercise
         such powers under this Credit Agreement or any other Credit Document as
         are delegated to the Administrative Agent by the terms hereof or
         thereof, together with such powers as are reasonably incidental
         thereto; and (G) such assignee agrees that it will


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<PAGE>
         perform in accordance with their terms all the obligations which by the
         terms of this Credit Agreement and the other Credit Documents are
         required to be performed by it as a Lender.

                  (c) Register. The Administrative Agent, acting solely for this
         purpose as an agent of the Borrower, shall maintain a copy of each
         Assignment Agreement delivered to and accepted by it and a register for
         the recordation of the names and addresses of the Lenders and the
         Commitment of, and principal amount of the Loans owing to, each Lender
         from time to time (the "Register"). The entries in the Register shall
         be conclusive and binding for all purposes, absent manifest error, and
         the Borrower, the Administrative Agent and the Lenders may treat each
         Person whose name is recorded in the Register as a Lender hereunder for
         all purposes of this Credit Agreement. The Register shall be available
         for inspection by the Borrower or any Lender at any reasonable time and
         from time to time upon reasonable prior notice.

                  (d) Acceptance. Upon its receipt of an Assignment Agreement
         executed by the parties thereto, together with any Note subject to such
         assignment and payment of the processing fee, the Administrative Agent
         shall, if such Assignment Agreement has been completed and is in
         substantially the form of Exhibit 11.3(b), (i) accept such Assignment
         Agreement, (ii) record the information contained therein in the
         Register and (iii) give prompt notice thereof to the parties thereto.

                  (e) Participations. Each Lender may sell participations to one
         or more Persons in all or a portion of its rights, obligations or
         rights and obligations under this Credit Agreement (including all or a
         portion of its Commitment and its Loans); provided, however, that (i)
         such Lender's obligations under this Credit Agreement shall remain
         unchanged, (ii) such Lender shall remain solely responsible to the
         other parties hereto for the performance of such obligations, (iii) the
         participant shall be entitled to the benefit of the yield protection
         provisions contained in Sections 3.9 through 3.15, inclusive (but not
         for a greater amount than the Lender would be entitled to), and of the
         right of set-off contained in Section 11.2, (iv) the Borrower shall
         continue to deal solely and directly with such Lender in connection
         with such Lender's rights and obligations under this Credit Agreement,
         and (v) such Lender shall retain the sole right to enforce the
         obligations of the Borrower relating to its Loans and its Notes and to
         approve any amendment, modification, or waiver of any provision of this
         Credit Agreement (other than amendments, modifications, or waivers
         decreasing the amount of principal of or the rate at which interest is
         payable on such Loans or Notes, extending any scheduled principal
         payment date or date fixed for the payment of interest on such Loans or
         Notes, extending its Commitment or releasing the Borrower or all or
         substantially all of the Guarantors from its or their respective
         obligations under the Credit Documents).

                  (f) Unrestricted Assignments. Notwithstanding any other
         provision set forth in this Credit Agreement, any Lender may at any
         time (i) assign and pledge all or any portion of its Loans and its
         Notes to any Federal Reserve Bank as collateral security pursuant to
         Regulation A and any Operating Circular issued by such Federal Reserve
         Bank or (ii) pledge all or any portion of its rights (but not its
         obligations to make Loans hereunder to any trustee or holders of
         obligations owed, or securities issued, by such


                                       73
<PAGE>
         Lender as security for such obligations or securities or to any other
         representative of such holders; provided that such trustee or holder
         shall not have the right to become a Lender hereunder. No such
         assignment shall release the assigning Lender from its obligations
         hereunder.

                  (g) Information. Any Lender may furnish any information
         concerning the Borrower or any of its Subsidiaries in the possession of
         such Lender from time to time to assignees and participants (including
         prospective assignees and participants), subject, however, to the
         provisions of Section 11.15.

                  (h) CLO's. Notwithstanding anything to the contrary contained
         herein, any Lender (a "Granting Lender") may grant to a special purpose
         funding vehicle (an "SPC") the option to fund all or any part of any
         Loan that such Granting Lender would otherwise be obligated to fund
         pursuant to this Credit Agreement; provided that (i) nothing herein
         shall constitute a commitment by any SPC to fund any Loan, (ii) if an
         SPC elects not to exercise such option or otherwise fails to fund all
         or any part of such Loan, the Granting Lender shall be obligated to
         fund such Loan pursuant to the terms hereof, (iii) no SPC shall have
         any voting rights pursuant to Section 11.6 and (iv) with respect to
         notices, payments and other matters hereunder, the Credit Parties, the
         Administrative Agent and the Lenders shall not be obligated to deal
         with an SPC, but may limit their communications and other dealings
         relevant to such SPC to the applicable Granting Lender. The funding of
         a Loan by an SPC hereunder shall utilize the Loan Commitment of the
         Granting Lender to the same extent that, and as if, such Loan were
         funded by such Granting Lender. Each party hereto hereby agrees that no
         SPC shall be liable for any indemnity or payment under this Credit
         Agreement for which a Lender would otherwise be liable for so long as,
         and to the extent, the Granting Lender provides such indemnity or makes
         such payment. Notwithstanding anything to the contrary contained in
         this Credit Agreement, any SPC may disclose on a confidential basis any
         non-public information relating to its funding of Loans to any rating
         agency, commercial paper dealer or provider of any surety or guarantee
         to such SPC. This clause (h) may not be amended without the prior
         written consent of each Granting Lender, all or any part of whose Loan
         is being funded by an SPC at the time of such amendment.

         11.4     NO WAIVER; REMEDIES CUMULATIVE.

         No failure or delay on the part of the Administrative Agent or any
Lender in exercising any right, power or privilege hereunder or under any other
Credit Document and no course of dealing between the Borrower or any Credit
Party and the Administrative Agent or any Lender shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, power or
privilege hereunder or under any other Credit Document preclude any other or
further exercise thereof or the exercise of any other right, power or privilege
hereunder or thereunder. The rights and remedies provided herein are cumulative
and not exclusive of any rights or remedies which the Administrative Agent or
any Lender would otherwise have. No notice to or demand on any Credit Party in
any case shall entitle any Credit Party to any other or further notice or demand
in similar or other circumstances or constitute a waiver of the rights of the
Administrative Agent or the Lenders to any other or further action in any
circumstances without notice or demand.


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<PAGE>
         11.5     PAYMENT OF EXPENSES; INDEMNIFICATION.

         The Borrower agrees to: (a) pay all reasonable out-of-pocket costs and
expenses of (i) the Agents and BAS in connection with (A) the negotiation,
preparation, execution and delivery, syndication and administration of this
Credit Agreement and the other Credit Documents and the documents and
instruments referred to therein (including, without limitation, the reasonable
fees and expenses of Moore & Van Allen, special counsel to the Administrative
Agent) and (B) any amendment, waiver or consent relating hereto and thereto
including, but not limited to, any such amendments, waivers or consents
resulting from or related to any work-out, renegotiation or restructure relating
to the performance by the Credit Parties under this Credit Agreement, and (ii)
the Administrative Agent and the Lenders in connection with (A) enforcement of
the Credit Documents and the documents and instruments referred to therein,
including, without limitation, in connection with any such enforcement, the
reasonable Attorneys' Costs of the Administrative Agent and each of the Lenders
and (B) any bankruptcy or insolvency proceeding of any Credit Party, and (b)
indemnify the Administrative Agent and each Lender, its officers, directors,
employees, representatives, counsel and agents from and hold each of them
harmless against any and all losses, liabilities, claims, damages or expenses
incurred by any of them as a result of, or arising out of, or in any way related
to, or by reason of, any investigation, litigation or other proceeding (whether
or not the Administrative Agent or any Lender is a party thereto) related to the
entering into and/or performance of any Credit Document or the use of proceeds
of any Loans (including other extensions of credit) hereunder or the
consummation of any other transactions contemplated in any Credit Document,
including, without limitation, reasonable Attorneys' Costs incurred in
connection with any such investigation, litigation or other proceeding (but
excluding any such losses, liabilities, claims, damages or expenses to the
extent incurred by reason of gross negligence or willful misconduct on the part
of the Person to be indemnified), (all of the foregoing, collectively,
"Indemnified Liabilities"). The agreements in this Section 11.5 shall survive
the termination of the Commitments and the repayment of the Credit Party
Obligations.

         11.6     AMENDMENTS, WAIVERS AND CONSENTS.

         Neither this Credit Agreement nor any other Credit Document nor any of
the terms hereof or thereof may be amended, changed, waived, discharged or
terminated unless such amendment, change, waiver, discharge or termination is in
writing and signed by the Required Lenders and the then Credit Parties; provided
that no such amendment, change, waiver, discharge or termination shall without
the consent of each Lender affected thereby:

                  (a) extend the Maturity Date or extend or postpone the time
         for any payment or prepayment of principal;

                  (b) reduce the rate or extend the time of payment of interest
         (other than as a result of waiving the applicability of any
         post-default increase in interest rates) thereon or fees hereunder;

                  (c) reduce or waive the principal amount of any Loan;


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<PAGE>
      (d) increase or extend the Commitment of a Lender (it being understood and
      agreed that a waiver of any Default or Event of Default shall not
      constitute a change in the terms of any Commitment of any Lender);

      (e) release the Borrower from its obligations or consent to the assignment
      or transfer by the Borrower of any of its rights and obligations under (or
      in respect of) the Credit Documents or release all or substantially all of
      the Guarantors from their respective obligations under the Credit
      Documents;

      (f) amend, modify or waive any provision of this Section 11.6 or Sections
      3.7, 3.8, 5.2, 9.1(a), 11.2, 11.3 or 11.5; or

      (g) reduce any percentage specified in, or otherwise modify, the
      definition of Required Lenders.

Notwithstanding the above, no provisions of Section 10 or Section 3.4 may be
amended or modified without the consent of the Administrative Agent.

Notwithstanding the fact that the consent of all the Lenders is required in
certain circumstances as set forth above, (x) each Lender is entitled to vote as
such Lender sees fit on any reorganization plan that affects the Loans and each
Lender acknowledges that the provisions of Section 1126(c) of the Bankruptcy
Code supersedes the unanimous consent provisions set forth herein and (y) the
Required Lenders may consent to allow a Credit Party to use cash collateral in
the context of a bankruptcy or insolvency proceeding.

         11.7     COUNTERPARTS/TELECOPY.

         This Credit Agreement may be executed in any number of counterparts,
each of which when so executed and delivered shall be an original, but all of
which shall constitute one and the same instrument. Delivery of executed
counterparts by telecopy shall be as effective as an original and shall
constitute a representation that an original will be delivered.

         11.8     HEADINGS.

         The headings of the sections and subsections hereof are provided for
convenience only and shall not in any way affect the meaning or construction of
any provision of this Credit Agreement.

         11.9     DEFAULTING LENDER.

         Each Lender understands and agrees that if such Lender is a Defaulting
Lender then notwithstanding the provisions of Section 11.6 it shall not be
entitled to vote on any matter requiring the consent of the Required Lenders or
to object to any matter requiring the consent of all the Lenders; provided,
however, that all other benefits and obligations under the Credit Documents
shall apply to such Defaulting Lender.


                                       76
<PAGE>
         11.10    SURVIVAL OF INDEMNIFICATION.

         All indemnities set forth herein shall survive the execution and
delivery of this Credit Agreement, the making of the Loans, the repayment of the
Loans and other obligations and the termination of the Commitments hereunder.

         11.11    GOVERNING LAW; VENUE; JURISDICTION.

                  (a) THIS CREDIT AGREEMENT AND THE OTHER CREDIT DOCUMENTS AND
         THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER AND THEREUNDER
         SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH
         THE LAWS OF THE STATE OF NEW YORK. Any legal action or proceeding with
         respect to this Credit Agreement or any other Credit Document may be
         brought in the courts of the State of New York or of the United States
         sitting in New York City, and, by execution and delivery of this Credit
         Agreement, each Credit Party hereby irrevocably accepts for itself and
         in respect of its Property, generally and unconditionally, the
         jurisdiction of such courts. Each Credit Party irrevocably consents to
         the service of process in any action or proceeding with respect to this
         Credit Agreement or any other Credit Document by the mailing of copies
         thereof by registered or certified mail, postage prepaid, to it at the
         address for notices pursuant to Section 11.1, such service to become
         effective 10 days after such mailing. Nothing herein shall affect the
         right of a Lender to serve process in any other manner permitted by law
         or to commence legal proceedings or otherwise proceed against a Credit
         Party in any other jurisdiction. Each Credit Party agrees that a final
         judgment in any action or proceeding shall be conclusive and may be
         enforced in other jurisdictions by suit on the judgment or in any other
         manner provided by law; provided that nothing in this Section 11.11(a)
         is intended to impair a Credit Party's right under applicable law to
         appeal or seek a stay of any judgment.

                  (b) Each Credit Party hereby irrevocably waives any objection
         which it may now or hereafter have to the laying of venue of any of the
         aforesaid actions or proceedings arising out of or in connection with
         this Credit Agreement or any other Credit Document in the courts
         referred to in subsection (a) hereof and hereby further irrevocably
         waives and agrees not to plead or claim in any such court that any such
         action or proceeding brought in any such court has been brought in an
         inconvenient forum.

         11.12    WAIVER OF JURY TRIAL; WAIVER OF CONSEQUENTIAL DAMAGES.

         EACH OF THE PARTIES TO THIS CREDIT AGREEMENT HEREBY IRREVOCABLY WAIVES
ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM ARISING OUT
OF OR RELATING TO THIS CREDIT AGREEMENT, ANY OF THE OTHER CREDIT DOCUMENTS OR
THE TRANSACTIONS CONTEMPLATED HEREBY. Each Credit Party agrees not to assert any
claim against the Administrative Agent, any Lender, any of their Affiliates, or
any of their respective directors, officers, employees, attorneys or agents, on
any theory of liability, for special, indirect, consequential or punitive
damages arising out of or otherwise relating to any of the transactions
contemplated herein.


                                       77
<PAGE>
         11.13    SEVERABILITY.

         If any provision of any of the Credit Documents is determined to be
illegal, invalid or unenforceable, such provision shall be fully severable and
the remaining provisions shall remain in full force and effect and shall be
construed without giving effect to the illegal, invalid or unenforceable
provisions.

         11.14    FURTHER ASSURANCES.

         The Credit Parties agree, upon the request of the Administrative Agent,
to promptly take such actions, as reasonably requested, as is necessary to carry
out the intent of this Credit Agreement and the other Credit Documents.

         11.15    CONFIDENTIALITY.

         Each Lender agrees that it will use its reasonable best efforts to keep
confidential and to cause any representative designated under Section 7.11 to
keep confidential any non-public information from time to time supplied to it
under any Credit Document; provided, however, that nothing herein shall prevent
the disclosure of any such information to (a) the extent a Lender in good faith
believes such disclosure is required by Requirement of Law, (b) counsel for a
Lender or to its accountants, (c) bank examiners or auditors or comparable
Persons, (d) any Affiliate of a Lender, (e) any other Lender, or any assignee,
transferee or participant, or any potential assignee, transferee or participant,
of all or any portion of any Lender's rights under this Credit Agreement who is
notified of the confidential nature of the information or (f) any other Person
in connection with any litigation to which any one or more of the Lenders is a
party if required by a court of law of competent jurisdiction. No Lender shall
have any obligation under this Section 11.15 to the extent any such information
becomes available on a non-confidential basis from a source other than a Credit
Party or that any information becomes publicly available other than by a breach
of this Section 11.15 by any Lender or representative thereof.

         11.16    ENTIRETY.

         This Credit Agreement together with the other Credit Documents and the
Fee Letter represent the entire agreement of the parties hereto and thereto, and
supersede all prior agreements and understandings, oral or written, if any,
including any commitment letters or correspondence relating to the Credit
Documents or the transactions contemplated herein and therein.

         11.17    BINDING EFFECT; CONTINUING AGREEMENT.

                  (a) This Credit Agreement shall become effective at such time
         when all of the conditions set forth in Section 5.1 have been satisfied
         or waived by the Lenders and it shall have been executed by the
         Borrower, the Guarantors and the Administrative Agent, and the
         Administrative Agent shall have received copies hereof (telefaxed or
         otherwise) which, when taken together, bear the signatures of each
         Lender, and thereafter this Credit Agreement shall be binding upon and
         inure to the benefit of the Borrower, the


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<PAGE>
      Guarantors, the Administrative Agent and each Lender and their respective
      successors and assigns.

                  (b) This Credit Agreement shall be a continuing agreement and
         shall remain in full force and effect until all Loans, interest, fees
         and other Credit Party Obligations have been paid in full and the
         Commitments have been terminated. Upon termination, the Credit Parties
         shall have no further obligations (other than the indemnification
         provisions that survive) under the Credit Documents; provided that
         should any payment, in whole or in part, of the Credit Party
         Obligations be rescinded or otherwise required to be restored or
         returned by the Administrative Agent or any Lender, whether as a result
         of any proceedings in bankruptcy or reorganization or otherwise, then
         the Credit Documents shall automatically be reinstated and all amounts
         required to be restored or returned and all costs and expenses incurred
         by the Administrative Agent or any Lender in connection therewith shall
         be deemed included as part of the Credit Party Obligations.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                       79
<PAGE>
         Each of the parties hereto has caused a counterpart of this Credit
Agreement to be duly executed and delivered as of the date first above written.

BORROWER:

                                            QUEST DIAGNOSTICS INCORPORATED,
                                            a Delaware corporation


                                            By: /s/ Joseph P. Manory
                                               ---------------------------------
                                            Name: Joseph P. Manory
                                               ---------------------------------
                                            Title: Vice President & Treasurer
                                               ---------------------------------


<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated

<TABLE>
<CAPTION>
GUARANTORS:
-----------
<S>                      <C>
                         QUEST DIAGNOSTICS HOLDINGS
                         INCORPORATED,
                         a Delaware corporation

                         QUEST DIAGNOSTICS CLINICAL
                         LABORATORIES, INC.,
                         a Delaware corporation

                         QUEST DIAGNOSTICS INCORPORATED,
                         a California corporation

                         QUEST DIAGNOSTICS INCORPORATED,
                         a Maryland corporation

                         QUEST DIAGNOSTICS INCORPORATED,
                         a Michigan corporation

                         QUEST DIAGNOSTICS OF PENNSYLVANIA, INC.,
                         a Delaware corporation

                         METWEST, INC.,
                         a Delaware corporation

                         NICHOLS INSTITUTE DIAGNOSTICS,
                         a California corporation

                         DPD HOLDINGS, INC.,
                         a Delaware corporation

                         DIAGNOSTICS REFERENCE SERVICES INC.,
                         a Maryland corporation

                         AMERICAN MEDICAL LABORATORIES,
                         INCORPORATED,
                         a Delaware corporation

                         AML INC.,
                         a Delaware corporation

                         QUEST DIAGNOSTICS INCORPORATED (NV),
                         a Nevada corporation
</TABLE>
<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated



                         MEDICAL LABORATORIES CORPORATION
                         d/b/a AMERICAN MEDICAL LABORATORIES,
                         a Virginia corporation

                         QUEST DIAGNOSTICS LLC,
                         an Illinois limited liability company

                         QUEST DIAGNOSTICS LLC,
                         a Connecticut limited liability company

                         QUEST DIAGNOSTICS LLC,
                         a Massachusetts limited liability company

                         APL PROPERTIES, LLC,
                         a Nevada limited liability company


                         By: /s/ Joseph P. Manory
                            -------------------------------------------
                         Name:  Joseph P. Manory
                         Title:  Vice President and Treasurer


                         PATHOLOGY BUILDING PARTNERSHIP,
                         a Delaware general partnership

                         By:  Quest Diagnostics Incorporated, a Maryland
                                  corporation, its general partner


                                  By: /s/ Joseph P. Manory
                                     -------------------------------------------
                                  Name:  Joseph P. Manory
                                  Title:  Vice President and Treasurer

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated

LENDERS:

                          BANK OF AMERICA, N.A.,
                          individually in its capacity as a Lender and in
                          its capacity as Administrative Agent



                          By: /s/ Philip Durand
                             --------------------------------------------------
                          Name: PHILIP S. DURAND
                               ------------------------------------------------
                          Title: MANAGING DIRECTOR
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          ALLFIRST BANK


                          By: /s/ Coney Burgess
                             --------------------------------------------------
                          Name: Coney Burgess
                               ------------------------------------------------
                          Title: Vice-President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          BANK HAPOALIM


                          By: /s/ Laura Anne Raffa
                             --------------------------------------------------
                          Name: Laura Anne Raffa
                               ------------------------------------------------
                          Title: Senior Vice President
                                -----------------------------------------------




                          By: /s/ Shaun Breidbart
                             --------------------------------------------------
                          Name: Shaun Breidbart
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          THE GOVERNOR & COMPANY OF THE BANK OF IRELAND


                          By: /s/ Geraldine Hannon
                             --------------------------------------------------
                          Name: Geraldine Hannon
                               ------------------------------------------------
                          Title: Authorized Signature
                                -----------------------------------------------




                          By: /s/ John S. Holt
                             --------------------------------------------------
                          Name: John S. Holt
                               ------------------------------------------------
                          Title: Authorized Signature
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          BANK LEUMI USA


                          By: /s/ Joung Hee Hong
                             --------------------------------------------------
                          Name: Joung Hee Hong
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          THE BANK OF NEW YORK


                          By: /s/ Christopher T. Kordes
                             --------------------------------------------------
                          Name: Christopher T. Kordes
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          BANK ONE, NA (MAIN OFFICE CHICAGO)


                          By: /s/ Joseph Pinzone
                             --------------------------------------------------
                          Name: Joseph Pinzone
                               ------------------------------------------------
                          Title: DIRECTOR
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          BAYERISCHE HYPOVEREINSBANK


                          By: /s/ Laura DePersis
                             --------------------------------------------------
                          Name: Laura DePersis
                               ------------------------------------------------
                          Title: Director
                                -----------------------------------------------




                          By: /s/ Diane Vaccaro
                             --------------------------------------------------
                          Name: Diane Vaccaro
                               ------------------------------------------------
                          Title: Associate Director
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          BNP PARIBAS


                          By: /s/ Alan Mustacchi
                             --------------------------------------------------
                          Name: Alan Mustacchi
                               ------------------------------------------------
                          Title: Managing Director
                                -----------------------------------------------




                          By: /s/ Ro Toyoshima
                             --------------------------------------------------
                          Name: RO TOYOSHIMA
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------


<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          CHANG HWA COMMERCIAL BANK, LTD.,
                          NEW YORK BRANCH


                          By: /s/ Ming-Hsien Lin
                             --------------------------------------------------
                          Name: Ming-Hsien Lin
                               ------------------------------------------------
                          Title: VP & General Manager
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          CHINATRUST COMMERCIAL BANK, LTD.,
                          NEW YORK BRANCH


                          By: /s/ Eric Kan
                             --------------------------------------------------
                          Name: Eric Kan
                               ------------------------------------------------
                          Title: SVP & Lending Manager
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          CREDIT LYONNAIS NEW YORK BRANCH


                          By: /s/ Charles Heidrieck
                             --------------------------------------------------
                          Name: Charles Heidrieck
                               ------------------------------------------------
                          Title: Senior Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          DEUTSCHE BANK SECURITIES INC.


                          By:            /s/ Irene Edges
                             --------------------------------------------------
                          Name:              Irene Edges
                               ------------------------------------------------
                          Title:             Director
                                -----------------------------------------------





                          By:             /s/ Iain Stewart
                             --------------------------------------------------
                          Name:               Iain Stewart
                               ------------------------------------------------
                          Title:              Director
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          E. SUN COMMERCIAL BANK, LTD.,
                          LOS ANGELES BRANCH



                          By:     /s/ Benjamin Lin
                             --------------------------------------------------
                          Name:   Benjamin Lin
                               ------------------------------------------------
                          Title:  EVP & General Manager
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          FLEET NATIONAL BANK



                          By:    /s/ Walter D. Maniello
                             --------------------------------------------------
                          Name:  Walter D. Maniello
                               ------------------------------------------------
                          Title: Managing Director
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          GENERAL ELECTRIC CAPITAL CORPORATION


                          By:    /s/ Janet K. Williams
                             --------------------------------------------------
                          Name:  JANET K. WILLIAMS
                               ------------------------------------------------
                          Title: DULY AUTHORIZED SIGNATORY
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          KEY CORPORATE CAPITAL INC.


                          By:    /s/ John M. Vandenderfer
                             --------------------------------------------------
                          Name:  JOHN M. VANDENDERFER
                               ------------------------------------------------
                          Title: SENIOR VICE PRESIDENT
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          LASALLE BANK NATIONAL ASSOCIATION


                          By:     /s/ Sarah Rusher
                             --------------------------------------------------
                          Name:   Sarah Rusher
                               ------------------------------------------------
                          Title:  Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          MERRILL LYNCH CAPITAL CORPORATION



                          By: /s/ Sheila McGillicuddy
                             --------------------------------------------------
                          Name: Sheila McGillicuddy
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated



                          MIZUHO CORPORATE BANK, LTD.


                          By: /s/ Greg Botshon
                             --------------------------------------------------
                          Name: Greg Botshon
                               ------------------------------------------------
                          Title: Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          NATIONAL CITY BANK


                          By: /s/ Tara M. Handforth
                             --------------------------------------------------
                          Name: Tara M. Handforth
                               ------------------------------------------------
                          Title: Assistant Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          THE NORINCHUKIN BANK, NEW YORK BRANCH


                          By: /s/ Furnieki Ono
                             --------------------------------------------------
                          Name: Furnieki Ono
                               ------------------------------------------------
                          Title: General Manager
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          PB CAPITAL CORPORATION



                          By: /s/ Kevin Watz
                             --------------------------------------------------
                          Name: KEVIN D. WATZ
                               ------------------------------------------------
                          Title: VICE PRESIDENT
                                -----------------------------------------------



                          By: /s/ Andrew L. Shipman
                             --------------------------------------------------
                          Name: ANDREW L. SHIPMAN
                               ------------------------------------------------
                          Title: ASSISTANT VICE PRESIDENT
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          PNC BANK, NATIONAL ASSOCIATION


                          By: /s/ Timothy J. Hornickle
                             --------------------------------------------------
                          Name: Timothy J. Hornickle
                               ------------------------------------------------
                          Title: Assistant Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          SUMITOMO MITSUI BANKING CORPORATION


                          By:          /s/ Edward D. Henderson, Jr.
                             --------------------------------------------------
                          Name:          Edward D. Henderson, Jr.
                               ------------------------------------------------
                          Title:          Joint General Manager
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          SUNTRUST BANK


                          By:    /s/ Mark D. Mathon
                             --------------------------------------------------
                          Name: Mark D. Mathon
                               ------------------------------------------------
                          Title:
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          UNION BANK OF CALIFORNIA, N.A.


                          By:             /s/ Gina M. West
                             --------------------------------------------------
                          Name:              Gina M. West
                               ------------------------------------------------
                          Title:            Vice President
                                -----------------------------------------------

<PAGE>
                  Signature Page to Term Loan Credit Agreement
                         Quest Diagnostics Incorporated


                          WACHOVIA BANK, NATIONAL ASSOCIATION


                          By:     /s/ Jessica Wright
                             --------------------------------------------------
                          Name:   Jessica Wright
                               ------------------------------------------------
                          Title:  Director
                                -----------------------------------------------




