
<PAGE>
 
                                                                     EXHIBIT 4.1


                        CLINICAL RESOURCE SYSTEMS, INC.

                               STOCK OPTION PLAN


                                   ARTICLE I
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                                    PURPOSE

     Clinical Resource Systems, Inc. (the "Company") is largely dependent for 
the successful conduct of its business on the initiative, effort and judgment of
its officers and employees and the officers and employees of its subsidiaries.
This Stock Option Plan (the "Plan") is intended to provide the key employees of
the Company and its subsidiaries an incentive through stock ownership in the 
Company and encourage them to remain in the Company's employ. Moreover, since 
the incentive stock options and non-qualified stock options provided for in the 
Plan are subject to various alternative provisions of the Internal Revenue Code 
of 1986, as amended (the "Code"), the Board of Directors of the Company (the 
"Board") will have considerable latitude in shaping stock options granted under 
the Plan to the particular circumstances of the optionee, thus recognizing the 
full value of the stock option.

                                  ARTICLE II
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                                ADMINISTRATION

     The Plan shall be administered by the Stock Option Committee (the 
"Committee"), the initial members of which shall be Charles B. Owen, M.D., 
Robert McConnell, M.D. and Don Pippin, Jr. The Committee shall at all times 
consist of not less than two members of the Board, and shall not include any 
persons that are not members of the Board. All members of the Committee shall 
be selected by (and serve at the pleasure of) the Board. All members of the 
Committee shall be "disinterested persons" within the meaning of Rule 16b-3 of 
the General Rules and Regulations under the Securities Exchange Act of 1934, as 
amended (the "1934 Act"). Subject to the express provisions of the Plan, the 
Committee shall have plenary authority, in its discretion, to recommend to the 
Board the individuals within the class set forth in Article IV to whom, and the 
                                                    ----------
time and price per share at which, stock options shall be granted, and the 
number of shares to be subject to each stock option. In making such 
recommendations and determinations, the Committee may take into account the 
nature of the services rendered by the respective employees, their present and 
potential contributions to the Company's success and such other factors as the 
Committee in its discretion shall deem relevant. Subject to the express 
provisions of the Plan, the Committee shall also have plenary authority to 
interpret the Plan, to prescribe, amend and rescind rules and regulations 
regulating it, to recommend to the Board the terms and provisions of the 
respective stock options (which need not be identical) and to make all other 
determinations necessary for advisable for the administration of the Plan. The 
Committee's determinations on the matters referred to in this Article II shall
                                                              ----------
be final, conclusive and binding upon all optionees.
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                                  ARTICLE III
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                  SHARES SUBJECT TO PLAN AND DURATION OF PLAN
      
     Under the Plan, a majority of the members of the Board who are 
disinterested persons may, upon recommendation of the Committee, at any time on 
or before ten (10) years after the date of adoption of the Plan or approval of 
the Plan by the shareholders of the Company, whichever is earlier, but not 
thereafter, grant to eligible persons stock options to purchase up to but not 
exceeding an aggregate of 600,000 shares of the Company's $0.002 par value 
Common Stock (subject to adjustment as provided in Article VIII).  Shares
                                                   ------------ 
subject to stock options under the Plan may be either authorized and unissued 
shares or issued shares which have been acquired by the Company and are being 
held in its treasury, in its sole discretion of the Board. When stock options 
have been granted under the Plan and have lapsed unexercised or partially 
unexercised or have been surrendered for cancellation by the optionee thereof, 
the shares which were subject thereto may be reoptioned under the Plan.

                                  ARTICLE IV
                                  ----------

                         ELIGIBILITY AND PARTICIPATION

     All officers and employees of the Company and its 50% or more owned 
subsidiaries (including 50% or more owned subsidiaries which become such after 
adoption of the Plan) shall be eligible to receive stock options under the Plan,
and employment by any of such subsidiaries shall constitute employment by the 
Company for purposes of this Plan; provided, however, that no member of the 
Committee shall be entitled to receive a stock option under this Plan while 
serving as a member of the Committee and for a period of one year thereafter.

                                   ARTICLE V
                                   ---------

                     TERMS AND CONDITIONS OF STOCK OPTIONS

     Each stock option granted under the Plan shall be evidenced by a stock 
option agreement (the "Agreement"), the form of which shall have been approved 
by the Committee and counsel to the Company. The Agreement shall be executed by 
the Company and the optionee and shall set forth the terms and conditions of the
option, which terms and conditions shall include, but not be limited to, the 
following:

           (a) Stock Option Price. The stock option price shall be
               ------------------
      determined by the Committee, but shall not in any event be less
      than the par value of the Company's Common Stock.

           (b) Term of Stock Option.  The term of the stock option shall be
               -------------------- 
     selected by the Committee, but in no event shall such term exceed
     ten (10) years from the date such stock option is granted.

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        (c)  Transferability. The stock options granted hereunder shall not be 
             --------------- 
     transferable otherwise than by will or operation of the laws of descent 
     and distribution or pursuant to a qualified domestic relations order as 
     defined in the Code or Title I of the Employee Retirement Income Security 
     Act, as amended, or the rules thereunder. During the lifetime of the 
     optionee, stock options granted hereunder shall be exercisable only by 
     the optionee or the optionee's guardian or legal representation.

        (d)  Exercise. Notwithstanding any other provision of this Plan, no 
             --------
     option shall be exercised more than ten (10) years from the date upon 
     which it is granted.

        (e)  Other Conditions. As its sole discretion, the Committee may impose 
             ----------------
     other conditions upon the options granted hereunder, including, but not 
     limited to, percentage limitations upon the exercisability of stock 
     options granted hereunder and termination of non-qualified stock options 
     on termination of employment.


                                  ARTICLE VI
                                  ----------

                            INCENTIVE STOCK OPTIONS

     The Committee and the Board, in recommending and granting stock options
hereunder, shall have the discretion to determine that certain stock options
shall be incentive stock options, as defined in Section 422 of the Code, while
other options shall be non-qualified stock options. Neither the members of the
Committee, the members of the Board nor the Company shall be under any
obligation or incur any liability to any person by reason of the determination
by the Committee or the Board whether a stock option granted under the Plan
shall be an incentive stock option or a non-qualified stock option. The
provisions of this Article VI shall be applicable to all incentive stock options
                   ----------
at any time granted or outstanding under the Plan.
   
     All incentive stock options granted or outstanding under the Plan shall be 
granted and held subject to and in compliance with the terms and conditions 
specifically set forth in Articles II, III, IV and V hereof and, in addition,
                          -------------------------- 
subject to and in compliance with the following further terms and conditions:

        (a)  the option price of all incentive stock options shall not be less 
     than one hundred percent (100%) of the fair market value of the Company's
     Common Stock at the time the stock option is granted (notwithstanding any
     provision of Article V hereof to the contrary);
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        (b) no incentive stock option shall be granted to any person who, at the
     time of the grant, owns stock possessing more than ten percent (10%) of the
     total combined voting power of all classes of stock of the Company or any
     parent or subsidiary of the Company, provided, however, that this 
     ownership limitation will be waived if, at the time the stock option is 
     granted, the stock option price is at least one hundred ten percent (110%)
     of the fair market value of the Company's Common Stock and such stock 
     option by its terms is not exercisable more than five (5) years from the 
     date it is granted;

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          (c)  the aggregate fair market value of all shares of Common Stock
     (determined at the time of the grant of the stock option) with respect to
     which incentive stock options are exercisable for the first time by any
     optionee during any one calendar year shall not exceed $100,000; and

          (d)  in the event of an optionee's termination of employment with the 
     Company for any reason other than death, all incentive stock options
     granted hereunder shall thereupon terminate; provided, however, the
     Committee may, in its discretion, direct that certain Agreements contain
     provisions permitting exercise of stock options after an optionee's
     retirement. Upon the termination of an optionee's employment by reason of
     his death, his incentive stock option shall terminate to the extent it was
     not exercisable at the date of his death, but to the extent it was then
     exercisable by the optionee, his estate or the beneficiaries thereof shall
     be entitled to exercise it for a period of one (1) year from the date of
     his death but not thereafter.

                                  ARTICLE VII
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                           EXERCISE OF STOCK OPTIONS

     Stock options granted hereunder may be exercised only by tendering to the 
Company written notice of exercise accompanied by the aggregate purchase price 
for the shares with respect to which the stock option is being exercised. No 
stock option shall be exercisable unless the shares issuable on the exercise 
thereof have been registered under the Securities Act of 1933, as amended (the 
"1933 Act"), or the Company shall have first received the opinion of its counsel
that registration under the 1933 Act is not required in connection with such 
issuance. At the time of exercise, if the shares with respect to which the stock
option is being exercised have not been registered under the 1933 Act, the
Company may require the optionee to give the Company whatever written assurance
counsel for the Company may require that the shares are being acquired for
investment and not with a view to the distribution thereof, and that the shares
will not be disposed of without the written opinion of such counsel that
registration under the 1933 Act is not required. Share certificates issued to
the optionee upon exercise of the stock option shall bear a legend to the
foregoing effect to the extent counsel for the Company deems it advisable. The
purchase price of shares of Common Stock of the Company acquired upon the
exercise of any non-qualified stock option or incentive stock option granted
under the Plan shall be paid in full by the optionee in cash or by certified or
cashier's check payable to the order of the Company, or by delivery to the
Company of shares of the Company's Common Stock theretofore owned by the
optionee having a fair market value equal to such stock option price, or by any
combination thereof. For purposes of the Plan, (i) if the shares of Common Stock
are traded on a stock exchange, shares of Common Stock shall be deemed to have a
fair market value equal to the average of the closing bid and asked price for a
share on such exchange for the trading day on which such value is being
determined, or (ii) if the shares of Common Stock are not traded on an exchange,
the shares shall be deemed to have a fair market value as is determined by the
Committee, which such determination of value shall be conclusive for the
purposes hereof if made in good faith by the Committee.
     
                                      -4-
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                                 ARTICLE VIII
                                 ------------

                                  ADJUSTMENTS

     Subject to any required action by the Company's directors and shareholders,
the number of shares provided for in each outstanding stock option and the price
per share thereof, and the number of shares provided for in the Plan, shall be
proportionately adjusted for any increase or decrease in the number of issued
shares of the Company's Common Stock resulting from a subdivision or
consolidation of shares or the payment of a stock dividend (but only on the
Common Stock) or any other increase or decrease in the number of such shares
effected without receipt of consideration by the Company. Subject to any
required action by the Company's directors and shareholders, if the Company
shall be the surviving corporation in any merger or consolidation, each
outstanding stock option shall pertain to and apply to the securities to which
a holder of the number of shares of the Company's Common Stock subject to the 
stock option would have been entitled. In the event of (a) a dissolution or
liquidation of the Company; (b) a consolidation or merger in which the Company
is not the surviving corporation; (c) a sale of all or substantially all of the
assets of the Company; or (d) a sale of all or substantially all of the
outstanding Common Stock of the Company to one purchaser, then each outstanding
stock option shall terminate; provided, however, that in such event, each
optionee shall have the right immediately prior to such dissolution or
liquidation, consolidation or merger in which the Company is not the surviving
corporation, sale of all or substantially all of the assets of the Company, or
sale of all or substantially all of the outstanding Common Stock of the Company
to one purchaser, to exercise his stock option with respect to the full number
of shares covered thereby, without regard to any installment provision contained
in his Agreement.

     In the event of a change in the Company's Common Stock which is limited to 
a change of all of its authorized shares with par value into the same number of 
shares with a different par value or without par value, the shares resulting 
from any such change shall be deemed to be Common Stock within the meaning of 
the Plan.  The aforesaid adjustments shall be made by the Committee whose 
determination in that respect shall be final, binding and conclusive.

     Except as hereinbefore expressly provided in this Article VIII, the 
                                                       ------------
optionee shall have no rights by reason of any subdivision or consolidation of 
shares of stock of any class or payment of any stock dividend or any other
increase or decrease in the number of shares of any class or by reason of any
dissolution or liquidation, merger or consolidation, sale of all or
substantially all assets, sale of all or substantially all of the outstanding
Common Stock of the Company, or spin-off of assets or stock of another
corporation; and any issue by the Company of shares of stock of any class, or
securities convertible into shares of stock of any class, shall not affect and
no adjustment by reason thereof shall be made with respect to the number or
price of shares of the Company's Common Stock subject to any stock option. The
grant of a stock option pursuant to the Plan shall not affect in any way the
right or power of the Company to make adjustments, reclassifications,
reorganizations or changes of its capital or business structure or to merge or
to consolidate or to dissolve or liquidate or sell or transfer all or any part
of its business or assets.

                                      -5-
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                                  ARTICLE IX
                                  ----------

                         PRIVILEGES OF STOCK OWNERSHIP

     No person entitled to exercise any stock option granted under the Plan 
shall have any of the rights or privileges of a shareholder of the Company in 
respect of any shares of stock issuable upon exercise of such stock option until
certificates representing such shares shall have been issued and delivered.

                                   ARTICLE X
                                   ---------

                          CONTINUATION OF EMPLOYMENT

     Nothing contained in the Plan (or in any stock option granted pursuant to 
the Plan) shall confer upon any employee any right to continue in the employ of
the Company or any subsidiary corporation or constitute any contract or 
agreement of employment or interfere in any way with the right of the Company 
or any subsidiary corporation to reduce any person's compensation from the rate 
in existence at the time of the granting of a stock option or to terminate such 
person's employment.  Nothing contained herein or in any Agreement shall affect 
any other contractual rights of an employee.

                                  ARTICLE XI
                                  ----------

                          AMENDMENT OR DISCONTINUANCE
 
     The Board or the Committee may at any time and from time to time amend,
rescind, suspend or terminate the Plan, as it shall deem advisable, provided, 
however, that the Plan may not be amended in any manner which would cause the 
Plan to no longer comply with Rule 16b-3 of the General Rules and Regulations 
under the 1934 Act, or any successor rule, or the provisions of the Code 
applicable to incentive stock options, as such rule or provision shall read as 
of the time of amendment.  In addition to Board approval of any amendment to the
Plan, if Rule 16b-3 of the General Rules and Regulations under the 1934 Act, or 
any successor rule, or the provisions of the  Code applicable to incentive stock
options, as such rule or provision shall read as of the time of amendment, 
requires shareholder approval of such amendment, then such amendment shall be 
approved by the holders of a majority of the voting stock of the Company (voting
as a single class) present, or represented, and entitled to vote at a meeting of
such shareholders duly held in accordance with the applicable laws of the state 
or other jurisdiction in which the Company is incorporated.

     No change may be made in, and no amendment, rescission, suspension or 
termination of the Plan shall have an effect on, stock options previously 
granted under the Plan which may impair or alter the rights or obligations of 
the holders thereof, except that any change may be made in stock options 
previously granted with the consent of the optionees.

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                                  ARTICLE XII
                                  -----------

                             SHAREHOLDER APPROVAL

     The Plan shall be effective as of March 31, 1989, the date on which it
received the approval of the Board. However, the Plan and all stock options
granted under the Plan shall be void if the Plan is not approved before March
30, 1990 by the holders of the outstanding voting stock of the Company by the
affirmative votes of the holders of a majority of the outstanding voting stock
of the Company present, or represented, and entitled to vote at a meeting duly
held in accordance with the applicable laws of the state or other jurisdiction
in which the Company is incorporated.

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