<SUBMISSION>
<ACCESSION-NUMBER>0001022079-04-000095
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>2
<PERIOD>20040503
<FILING-DATE>20040504
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BONGIORNO THOMAS F
<CIK>0001222675
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12215
<FILM-NUMBER>04778890
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>QUEST DIAGNOSTICS INC
<STREET2>ONE MALCOLM AVE
<CITY>TETERBORO
<STATE>NJ
<ZIP>07608
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>QUEST DIAGNOSTICS INC
<CIK>0001022079
<ASSIGNED-SIC>8071
<IRS-NUMBER>161387862
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>ONE MALCOLM AVE
<CITY>TETERBORO
<STATE>NJ
<ZIP>07608
<PHONE>2013935000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>ONE MALCOLM AVE
<CITY>TETERBORO
<STATE>NJ
<ZIP>07601
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>CORNING CLINICAL LABORATORIES INC
<DATE-CHANGED>19960903
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-05-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001022079</issuerCik>
        <issuerName>QUEST DIAGNOSTICS INC</issuerName>
        <issuerTradingSymbol>DGX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222675</rptOwnerCik>
            <rptOwnerName>BONGIORNO THOMAS F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP &amp; Corporate Controller</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2443</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>85</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>91</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>117</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These underlying shares were acquired on a periodic basis by the trustee of the Company's tax qualified Profit Sharing (401(k)) plan and/or the Company's Supplemental Deferred Compensation Plan.  The information was obtained from the plan administrator as of a recent date.  The number of shares is based on the account balance of the Company stock fund under the plan (which includes some money market instruments) divided by the market price of the Company's stock as of that date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Sirisha Gummaregula, for Thomas F. Bongiorno</signatureName>
        <signatureDate>2004-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>bongiornopoa-50404.txt
<DESCRIPTION>POWER OF ATTORNEY
<TEXT>
POWER OF ATTORNEY


	Know all by these presents, that the undersigned hereby
constitutes and appoints each of Sirisha Gummaregula, Michael E.
Prevoznik, and Leo C. Farrenkopf, Jr., signing singly, the
undersigned's true and lawful attorney-in-fact to:

(1)	execute for and on behalf of the undersigned, in the
undersigned's capacity as an executive officer and/or director of
Quest Diagnostics Incorporated (the "Company"), Form ID Applications
and Forms 3, 4 and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder;

(2)	do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete and
execute any such Form ID Application, Form 3, 4 or 5, complete and
execute any amendment or amendments thereto, and timely  file such
form with the United States Securities and Exchange Commission and
any other authority; and

(3)	take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-fact,
may be of benefit to, in the best interest of, or legally required
by, the undersigned, it being understood that the documents executed
by such attorney-in-fact on behalf of the undersigned pursuant to this
Power of Attorney shall be in such form and shall contain such terms
and conditions as such attorney-in-fact may approve in such attorney-
in-fact's discretion.

	The undersigned hereby grants to each such attorney-in-fact
full power and authority to do and perform all and every act and thing
whatsoever requisite, necessary and proper to be done in the exercise
of any of the rights and powers herein granted, as fully to all intents
and purposes as the undersigned might or could do if personally present,
with full power of substitution or revocation, hereby ratifying and
confirming all that such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause to be done by
virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing attorneys-
in-fact, in serving in such capacity at the request of the undersigned,
are not assuming, nor is the company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange
Act of 1934.

	This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4, and 5
with respect to the undersigned's holdings of and transactions in
securities issued by the Company, unless earlier revoked by the
undersigned in a signed writing delivered to the foregoing attorneys-
in-fact.

	IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 4th day of May, 2004.

	/s/Thomas F. Bongiorno
	Signature
	THOMAS F. BONGIORNO



STATE OF NEW JERSEY	)
	  ):  ss.
COUNTY OF BERGEN	  )

	On this 4th day of May, 2004, before me, the subscriber,
personally appeared THOMAS F. BONGIORNO, to me and known to me to be
the same person described in and who executed the foregoing instrument,
and he duly acknowledged to me that he executed the same.


	/s/Angela Del Casale
	Notary Public
	Notary Public of New Jersey
	My Commission Expires Sept. 20, 2006

</TEXT>
</DOCUMENT>
</SUBMISSION>
