-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001104706-06-000006.txt : 20060404
<SEC-HEADER>0001104706-06-000006.hdr.sgml : 20060404
<ACCEPTANCE-DATETIME>20060404150113
ACCESSION NUMBER:		0001104706-06-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060331
FILED AS OF DATE:		20060404
DATE AS OF CHANGE:		20060404

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NATIONAL PATENT DEVELOPMENT CORP
		CENTRAL INDEX KEY:			0001279715
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS MANUFACTURING INDUSTRIES [3990]
		IRS NUMBER:				134005439
		STATE OF INCORPORATION:			DE

	BUSINESS ADDRESS:	
		STREET 1:		777 WESTCHESTER AVE.
		STREET 2:		FOURTH FLOOR
		CITY:			WHITE PLAINS
		STATE:			NY
		ZIP:			10640

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			EISEN HARVEY P
		CENTRAL INDEX KEY:			0001104706

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50587
		FILM NUMBER:		06737543

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		9142425725

	MAIL ADDRESS:	
		STREET 1:		100 SOUTH BEDFORD ROAD
		CITY:			MT KISCO
		STATE:			NY
		ZIP:			10549
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-31</periodOfReport>

    <issuer>
        <issuerCik>0001279715</issuerCik>
        <issuerName>NATIONAL PATENT DEVELOPMENT CORP</issuerName>
        <issuerTradingSymbol>NPDV</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001104706</rptOwnerCik>
            <rptOwnerName>EISEN HARVEY P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BEDFORD OAK PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>100 SOUTH BEDFORD ROAD</rptOwnerStreet2>
            <rptOwnerCity>MOUNT KISCO</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10549</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>2006-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>851</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.47</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5223</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2431500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Bedford Oak Partners, LP</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Quarterly Director's Fee</footnote>
        <footnote id="F2">Shares owned directly by Bedford Oak Partners, L.P. (the &quot;Partnership&quot;).  A portion of these securities may also be deemed to be  owned beneficially indirectly by Bedford Oak Management LLC, the general partner of the Partnership (the &quot;General Partner&quot;), and by Harvey P. Eisen, the Managing Member of the General Parnter, in accordance with the respective &quot;pecuniary interests&quot; of such persons (within the meaning of Exchange Act Rule 16a-1(a)(2).  An affiliated entity, Bedford Oak Advisors, LLC as investment manger of the Partnership (&quot;Advisors&quot;) has the power to vote and dipose of such shares but has no pecuniary interest therein.  The General Partner and Mr. Eisen disclain any beneficial interest in such securities in excess of such pecuniary interest.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Harvey P. Eisen</signatureName>
        <signatureDate>2006-04-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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