-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001127602-09-002566.txt : 20090204
<SEC-HEADER>0001127602-09-002566.hdr.sgml : 20090204
<ACCEPTANCE-DATETIME>20090204163910
ACCESSION NUMBER:		0001127602-09-002566
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090202
FILED AS OF DATE:		20090204
DATE AS OF CHANGE:		20090204

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUEST DIAGNOSTICS INC
		CENTRAL INDEX KEY:			0001022079
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-MEDICAL LABORATORIES [8071]
		IRS NUMBER:				161387862
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3 GIRALDA FARMS
		CITY:			MADISON
		STATE:			NJ
		ZIP:			07940
		BUSINESS PHONE:		9735202700

	MAIL ADDRESS:	
		STREET 1:		3 GIRALDA FARMS
		CITY:			MADISON
		STATE:			NJ
		ZIP:			07940

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CORNING CLINICAL LABORATORIES INC
		DATE OF NAME CHANGE:	19960903

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MOHAPATRA SURYA N
		CENTRAL INDEX KEY:			0001222671

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12215
		FILM NUMBER:		09568744

	BUSINESS ADDRESS:	
		STREET 1:		QUEST DIAGNOSTICS INC
		STREET 2:		ONE MALCOLM AVE
		CITY:			TETERBORO
		STATE:			NJ
		ZIP:			07608
		BUSINESS PHONE:		973-520-2187

	MAIL ADDRESS:	
		STREET 1:		3 GIRALDA FARMS
		CITY:			MADISON
		STATE:			NJ
		ZIP:			07940
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-02-02</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222671</rptOwnerCik>
            <rptOwnerName>MOHAPATRA SURYA N</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O QUEST DIAGNOSTICS INCORPORATED</rptOwnerStreet1>
            <rptOwnerStreet2>3 GIRALDA FARMS</rptOwnerStreet2>
            <rptOwnerCity>MADISON</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07940</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <officerTitle>Chairman, President &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10884</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>49.2513</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>176947</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10884</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>49.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>166063</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5094</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k)/sdcp</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>49.2513</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-02-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10884</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-02-08</value>
            </exerciseDate>
            <expirationDate>
                <value>2009-02-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10884</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The exercise and sale reported were effected pursuant to a Rule 10b5-1 sales plan adopted by the reporting person on November 21, 2008.</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)) and/or Supplemental Deferred Compensation Plan.  The information was obtained from the plan administrator as of a current date.  The number of shares is based on the account balance of the Company stock fund under each 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>/s/ William J. O'Shaughnessy, Jr., Attorney in Fact for Surya N. Mohapatra</signatureName>
        <signatureDate>2009-02-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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