-----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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 4IwGpfOqoiQ0P6OpxLbC4w==

<SEC-DOCUMENT>0000939713-06-000021.txt : 20060403
<SEC-HEADER>0000939713-06-000021.hdr.sgml : 20060403
<ACCEPTANCE-DATETIME>20060403095739
ACCESSION NUMBER:		0000939713-06-000021
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060331
FILED AS OF DATE:		20060403
DATE AS OF CHANGE:		20060403

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			INTERPOOL INC
		CENTRAL INDEX KEY:			0000898777
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-EQUIPMENT RENTAL & LEASING, NEC [7359]
		IRS NUMBER:				133467669
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		211 COLLEGE RD E
		CITY:			PRINCTON
		STATE:			NJ
		ZIP:			08540
		BUSINESS PHONE:		6094528900

	MAIL ADDRESS:	
		STREET 1:		211 COLLEGE ROAD EAST
		CITY:			PRINCETON
		STATE:			NJ
		ZIP:			08540

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			TUCHMAN MARTIN
		CENTRAL INDEX KEY:			0000939713

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11862
		FILM NUMBER:		06731457

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		6094528900

	MAIL ADDRESS:	
		STREET 1:		633 PROSPECT AVE
		CITY:			PRINCETON
		STATE:			NJ
		ZIP:			08540
</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>2006-03-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000898777</issuerCik>
        <issuerName>INTERPOOL INC</issuerName>
        <issuerTradingSymbol>IPX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000939713</rptOwnerCik>
            <rptOwnerName>TUCHMAN MARTIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>633 PROSPECT AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PRINCETON</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08540</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CoB, CEO, President &amp; COO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>600</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6975274</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This stock was sold pursuant to a 105B-1 plan.</footnote>
        <footnote id="F2">Includes 255,002 shares held indirectly including 8,668 shares held by a pension plan for the benefit of reporting person, 46,619 shares held in a revocable trust where the reporting person in the Trustee, 182,381 shares owned by a corporation in which the reporting person holda a 90% interest, 5,797 shares owned by a company in which the reporting person holds a 51.304% interest, 7,000 shares owned by a foundation of which the reporting person is the Trustee,  1,500 shares held by the spouse's IRA and 3,037 shares held by spouse.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Martin Tuchman</signatureName>
        <signatureDate>2006-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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