-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 LvpAda5DYx7csBBZ/9lb6WLk7rkN2DRfcnMA/tfXgT1JM8guFOgdvyxvjki0q1ft
 z9d/T0HvGHFsdTSGEh+7SQ==

<SEC-DOCUMENT>0001193162-04-000014.txt : 20040623
<SEC-HEADER>0001193162-04-000014.hdr.sgml : 20040623
<ACCEPTANCE-DATETIME>20040623160030
ACCESSION NUMBER:		0001193162-04-000014
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040623
FILED AS OF DATE:		20040623

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MERRIMAC INDUSTRIES INC
		CENTRAL INDEX KEY:			0000706864
		STANDARD INDUSTRIAL CLASSIFICATION:	RADIO & TV BROADCASTING & COMMUNICATIONS EQUIPMENT [3663]
		IRS NUMBER:				221642321
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0102

	BUSINESS ADDRESS:	
		STREET 1:		41 FAIRFIELD PL
		CITY:			W CALDWELL
		STATE:			NJ
		ZIP:			07006-0986
		BUSINESS PHONE:		9735751300

	MAIL ADDRESS:	
		STREET 1:		41 FAIRFIELD PLACE
		CITY:			WEST CALDWELL
		STATE:			NJ
		ZIP:			07007-0986

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COHEN EDWARD H
		CENTRAL INDEX KEY:			0001188536

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09970
		FILM NUMBER:		04877437

	BUSINESS ADDRESS:	
		STREET 1:		KMZ ROSENMAN
		STREET 2:		575 MADISON AVE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		2129408580

	MAIL ADDRESS:	
		STREET 1:		KMZ ROSENMAN
		STREET 2:		575 MADISON AVE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-06-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000706864</issuerCik>
        <issuerName>MERRIMAC INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>MRM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001188536</rptOwnerCik>
            <rptOwnerName>COHEN EDWARD H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>KMZ ROSENMAN</rptOwnerStreet1>
            <rptOwnerStreet2>575 MADISON AVE</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-06-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.06</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ Robert V. Condon, Attorney in Fact</signatureName>
        <signatureDate>2004-06-23</signatureDate>
    </ownerSignature>
</ownershipDocument>

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