<SUBMISSION>
<ACCESSION-NUMBER>0001022079-04-000156
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>2
<PERIOD>20040813
<FILING-DATE>20040817
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>ZEWE DAVID M
<CIK>0001222680
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12215
<FILM-NUMBER>04982083
</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>2004-08-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222680</rptOwnerCik>
            <rptOwnerName>ZEWE DAVID M</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>SVP, Diagnostic Testing Ops</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-08-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.17</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27148</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-08-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>82.101</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>18498</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2481</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401K/SDCP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.17</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-08-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1999-08-16</value>
            </exerciseDate>
            <expirationDate>
                <value>2009-08-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8650</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31350</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Certain of these shares are subject to restrictions on transfer, the possibility of forfeiture and/or certain other terms contained in the underlying stock agreements and related plan documents.</footnote>
        <footnote id="F2">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</signatureName>
        <signatureDate>2004-08-17</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>zewepoa-050504.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 5th day of May, 2004.


	/s/David M. Zewe
	Signature
	DAVID M. ZEWE



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

	On this 5th day of May, 2004, before me,
the subscriber, personally appeared DAVID W.  ZEWE,
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>
