-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Owwb7jI+mJqO+aQ2pISVcgHO0XCfcQL6iCY/YwFmF+IQb4YTKmNahuEsUAs5HWaP
 5TyIVWlhU0mZ8Z2joJSMQQ==

<SEC-DOCUMENT>0001209191-03-037185.txt : 20031231
<SEC-HEADER>0001209191-03-037185.hdr.sgml : 20031231
<ACCEPTANCE-DATETIME>20031231120521
ACCESSION NUMBER:		0001209191-03-037185
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031230
FILED AS OF DATE:		20031231

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:		031079713

	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>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-30</periodOfReport><notSubjectToSection16>0</notSubjectToSection16>
    <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>ONE MERCK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 100</rptOwnerStreet2>
            <rptOwnerCity>WHITEHOUSE STATION</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08889-0100</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Pres.Merck Vaccines</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Phantom Stock</value></securityTitle><conversionOrExercisePrice><footnoteId id="F1" /></conversionOrExercisePrice><transactionDate><value>2003-12-30</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>22.8941</value></transactionShares><transactionPricePerShare><value>45.5000</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F2" /></exerciseDate><expir
ationDate><footnoteId id="F3" /></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>22.8941</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>250.7555</value><footnoteId id="F4" /></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">1-for-1</footnote><footnote id="F2">The Merck Deferral Program includes the right of redesignation to other investment measures within the Program.</footnote><footnote id="F3">Distributions of phantom stock are made in shares of 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 Deferr
al Program.</footnote><footnote id="F4">Holdings include shares acquired in dividend reinvestment transactions.</footnote></footnotes><remarks></remarks><ownerSignature><signatureName>Nancy V. Van Allen as Attorney-in-Fact for
Adel Mahmoud</signatureName><signatureDate>2003-12-31</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----