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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 eYK2nfwuVmOr19yXZc6pXQ==

<SEC-DOCUMENT>0001209191-03-009143.txt : 20030723
<SEC-HEADER>0001209191-03-009143.hdr.sgml : 20030723
<ACCEPTANCE-DATETIME>20030630114150
ACCESSION NUMBER:		0001209191-03-009143
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030627
FILED AS OF DATE:		20030630

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MAHMOUD ADEL
		CENTRAL INDEX KEY:			0001181181

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-03305
		FILM NUMBER:		03763095

	BUSINESS ADDRESS:	
		STREET 1:		MERCK & CO INC
		STREET 2:		ONE MERCK DR PO BOX 100
		CITY:			WHITEHOUSE STATION
		STATE:			NJ
		ZIP:			08889
		BUSINESS PHONE:		9084231000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MERCK & CO INC
		CENTRAL INDEX KEY:			0000064978
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				221109110
		STATE OF INCORPORATION:			NJ
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ONE MERCK DR
		STREET 2:		P O BOX 100
		CITY:			WHITEHOUSE STATION
		STATE:			NJ
		ZIP:			08889-0100
		BUSINESS PHONE:		9084234044

	MAIL ADDRESS:	
		STREET 1:		ONE MERCK DR
		STREET 2:		PO BOX 100 WS3AB-05
		CITY:			WHITEHOUSE STATION
		STATE:			NJ
		ZIP:			08889-0100
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?><ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-06-27</periodOfReport>
    <issuer>
        <issuerCik>0000064978</issuerCik>
        <issuerName>MERCK &amp; CO INC</issuerName>
        <issuerTradingSymbol>(MRK)</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001181181</rptOwnerCik>
            <rptOwnerName>MAHMOUD ADEL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Pres.Merck Vaccines</officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Phantom Stock</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F1" /></conversionOrExercisePrice><transactionDate><value>2003-06-27</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>17.0711</value></transactionShares><transactionValue><value>61.02</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value><footnoteId id="F2" /></exerciseDate><expirationDate><value>
1988-08-08</value><footnoteId id="F3" /></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>17.0711</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>109.8188</value><footnoteId id="F4" /></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">1-for-1</footnote><footnote id="F2">[This date entry is made pursuant to SEC EDGAR guidelines in effect until system modifications are implemented.]  The Merck Deferral Program includes the right of redesignation to other investment measures within the Program.</footnote><footnote id="F3">[This date entry is made pursuant to SEC EDGAR guidelines in effect until system modifications are implemented.]  Distributions of phantom stock are made in shares o
f Merck Common Stock, with cash payable for partial shares, in accordance with a distribution schedule elected by the reporting person.  This distribution is subject to conditions and limitations of the Merck Deferral Program.</footnote><footnote id="F4">Holdings include shares acquired in dividend reinvestment transactions.</footnote></footnotes><ownerSignature><signatureName>Nancy V. Van Allen as Attorney-in-Fact for
Adel Mahmoud</signatureName><signatureDate>2003-06-30</signatureDate></ownerSignature></ownershipDocument>

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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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