<SEC-DOCUMENT>0001022079-16-000256.txt : 20160509
<SEC-HEADER>0001022079-16-000256.hdr.sgml : 20160509
<ACCEPTANCE-DATETIME>20160509161917
ACCESSION NUMBER:		0001022079-16-000256
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20160506
FILED AS OF DATE:		20160509
DATE AS OF CHANGE:		20160509

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:			Cunningham Everett
		CENTRAL INDEX KEY:			0001564777

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12215
		FILM NUMBER:		161631911

	MAIL ADDRESS:	
		STREET 1:		C/O QUEST DIAGNOSTICS, 3 GIRALDA FARMS
		CITY:			MADISON
		STATE:			NJ
		ZIP:			07940
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_146282513291782.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2016-05-06</periodOfReport>

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    <issuer>
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        <issuerName>QUEST DIAGNOSTICS INC</issuerName>
        <issuerTradingSymbol>DGX</issuerTradingSymbol>
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            <rptOwnerName>Cunningham Everett</rptOwnerName>
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            <rptOwnerStreet1>C/O QUEST DIAGNOSTICS INCORPORATED</rptOwnerStreet1>
            <rptOwnerStreet2>3 GIRALDA FARMS</rptOwnerStreet2>
            <rptOwnerCity>MADISON</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07940</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
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            <officerTitle>SVP, Commercial</officerTitle>
            <otherText></otherText>
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            <transactionAmounts>
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                    <value>949</value>
                </transactionShares>
                <transactionPricePerShare>
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            </transactionDate>
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                <transactionFormType>4</transactionFormType>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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                    <footnoteId id="F2"/>
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                <directOrIndirectOwnership>
                    <value>I</value>
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                    <value>401(k)</value>
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            </ownershipNature>
        </nonDerivativeHolding>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
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            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-05-06</value>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-02-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>949.0</value>
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            </underlyingSecurity>
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            </transactionDate>
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            </expirationDate>
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                    <value>D</value>
                </directOrIndirectOwnership>
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        <derivativeTransaction>
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                <value>2016-05-06</value>
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                    <value>71.17</value>
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                    <value>D</value>
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                <footnoteId id="F5"/>
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            <expirationDate>
                <value>2025-02-23</value>
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                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
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    <footnotes>
        <footnote id="F1">The amount includes exempt purchases made under the Company's stock purchase plan since the date of the last filing on Form 4.</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. 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 the Plan (which includes some money market instruments) divided by the market price of the Company's stock as of that date.</footnote>
        <footnote id="F3">The options, granted on February 25, 2013, vest in three equal annual installments beginning on the first annual anniversary of the grant date.</footnote>
        <footnote id="F4">The options, granted on February 13, 2014, vest in three equal annual installments beginning on the first annual anniversary of the grant date.</footnote>
        <footnote id="F5">The options, granted on February 23, 2015, vest in three equal annual installments beginning on the first annual anniversary of the grant date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>William J. O'Shaughnessy, Jr., Attorney in Fact for Everett Cunningham</signatureName>
        <signatureDate>2016-05-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
