<SUBMISSION>
<ACCESSION-NUMBER>0000903423-06-000645
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20060607
<FILING-DATE>20060609
<DATE-OF-FILING-DATE-CHANGE>20060609
<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>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>GLAXOSMITHKLINE PLC
<CIK>0001131399
<ASSIGNED-SIC>2834
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12215
<FILM-NUMBER>06898129
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>980 GREAT WEST ROAD
<CITY>BRENTFORD MIDDLESEX
<STATE>X0
<ZIP>TW8 9GS
<PHONE>011442080475000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>980 GREAT WEST ROAD
<CITY>BRENTFORD MIDDLESEX
<STATE>X0
<ZIP>TW8 9GS
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>glaxoquest-f4_0609ex.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-06-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001131399</rptOwnerCik>
            <rptOwnerName>GLAXOSMITHKLINE PLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>980 GREAT WEST ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BRENTFORD MIDDLESEX</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>TW8 9GS</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>36504308</value>
                    <footnoteId id="F7"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Contract to Sell</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
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                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
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            <transactionDate>
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                <footnoteId id="F5"/>
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            <transactionCoding>
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                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
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                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
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                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Contract to Sell</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-07</value>
            </transactionDate>
            <deemedExecutionDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Contract to Sell</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-07</value>
            </transactionDate>
            <deemedExecutionDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Contract to Sell</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-07</value>
            </transactionDate>
            <deemedExecutionDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Contract to Sell</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-07</value>
            </transactionDate>
            <deemedExecutionDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Corporation</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On May 21, 2002, SmithKline Beecham Corporation (&quot;SKB&quot;) and Lehman Brothers Finance S.A. (&quot;Lehman&quot;) entered into five
 transactions (each, a &quot;Transaction&quot;) governed by an ISDA Master Agreement, each of which initially related to 1,000,000
 shares of Common Stock of the Issuer (the &quot;Shares&quot;).  At the time of extension described below, each Transaction related to
 2,000,000 Shares as a result of a stock split on June 20, 2005.</footnote>
        <footnote id="F2">On June 7, 2006, each Transaction was extended.  As extended, the Transactions provide for SKB to deliver to Lehman, for
 settlement on November 11, 2010 (&quot;Transaction 1&quot;), August 10, 2012 (&quot;Transaction 2&quot;), April 12, 2010 (&quot;Transaction 3&quot;), June
 10, 2011 (&quot;Transaction 4&quot;) and January 12, 2012 (&quot;Transaction 5&quot;), a number of Shares (the &quot;Settlement Shares&quot;) to be
 determined based on the formula described in the Reporting Person's filing on Form 4 dated June 8, 2002, as follows:  If the
 price of the Shares determined near the original settlement date of a Transaction (the &quot;Final Price&quot;) is at or below a
 specified Depreciation Floor ($41.19 per Share for Transaction 1, $40.60 for Transaction 2, $41.30 for Transaction 3, $40.96
 for Transaction 4 and $40.73 for Transaction 5), SKB will be obligated to deliver all the Shares underlying that particular
 Transaction.</footnote>
        <footnote id="F3">If the Final Price is above the specified Depreciation Floor and at or below a specified Appreciation Cap as defined in each
 Transaction ($53.49 per Share for Transaction 1, $60.98 for Transaction 2, $52.08 for Transaction 3, $55.38 for Transaction
 4 and $57.68 for Transaction 5), SKB will be obligated to deliver a number of Shares equal to the number of Shares
 underlying that particular Transaction multiplied by the Depreciation Floor divided by the Final Price.  If the Final Price
 is above the specified Appreciation Cap, SKB will be obligated to deliver a number of Shares equal to the number of Shares
 underlying that particular Transaction multiplied by (i) 1.0 minus (ii) (a) the Appreciation Cap minus the Depreciation
 Floor divided by (b) the Final Price.</footnote>
        <footnote id="F4">In any case, Lehman is obligated to pay SKB under each Transaction upon settlement an amount equal to the sum of (i) the
 product of (A) the Settlement Shares multiplied by (B) the lesser of (x) the Extended Appreciation Cap ($63.88 for
 Transaction 1, $67.28 for Transaction 2, $62.75 for Transaction 3, $65.02 for Transaction 4, $66.15 for Transaction 5) and
 (y) the greater of (1) the Extended Depreciation Floor ($49.57) and (2) the price of the Shares determined near the extended
 settlement date of a Transaction (the &quot;Extended Final Price&quot;), plus (ii) the product of (A) the excess of 2,000,000 over the
 Settlement Shares multiplied by (continued in footnote 5)</footnote>
        <footnote id="F5">(B) if (x) the Extended Final Price is less than or equal to the Extended Depreciation Floor, the Extended Depreciation Floor
 minus the Extended Final Price, (y) the Extended Final Price is greater that the Extended Appreciation Cap, the Extended
 Appreciation Cap minus the Extended Final Price or (z) if the Extended Final Price is greater than the Extended Depreciation
 Floor and less than or equal to the Extended Appreciation Cap, zero. The Adjustment Letter evidencing the extension of the
 Transactions will be filed as an Exhibit to Amendment No. 5 to Schedule 13D to be filed by the Reporting Person.</footnote>
        <footnote id="F6">Shares are held of record by SKB, a wholly owned subsidiary of Reporting Person.</footnote>
        <footnote id="F7">Adjusted to reflect the two-for-one stock split effected by the Issuer on June 20, 2005.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Donald F. Parman, Vice President &amp; Assoc General Counsel</signatureName>
        <signatureDate>2006-06-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
