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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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<SEC-DOCUMENT>0000833640-09-000012.txt : 20090105
<SEC-HEADER>0000833640-09-000012.hdr.sgml : 20090105
<ACCEPTANCE-DATETIME>20090105192440
ACCESSION NUMBER:		0000833640-09-000012
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081231
FILED AS OF DATE:		20090105
DATE AS OF CHANGE:		20090105

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bailey Doug
		CENTRAL INDEX KEY:			0001389039

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-23441
		FILM NUMBER:		09507756

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		408-414-9200

	MAIL ADDRESS:	
		STREET 1:		5245 HELLYER AVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95138

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			POWER INTEGRATIONS INC
		CENTRAL INDEX KEY:			0000833640
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				943065014
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		5245 HELLYER AVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95138
		BUSINESS PHONE:		4084149200

	MAIL ADDRESS:	
		STREET 1:		5245 HELLYER AVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95138
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-12-31</periodOfReport>

    <issuer>
        <issuerCik>0000833640</issuerCik>
        <issuerName>POWER INTEGRATIONS INC</issuerName>
        <issuerTradingSymbol>POWI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001389039</rptOwnerCik>
            <rptOwnerName>Bailey Doug</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5245 HELLYER AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95138</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP Marketing</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>31.15</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-10-29</value>
            </exerciseDate>
            <expirationDate>
                <value>2018-04-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The options were tendered in exchange for payment of $4.00 per underlying share of Common Stock pursuant to an issuer tender offer described in the Tender Offer Statement on Schedule TO filed with the Commission on December 3, 2008, as amended on December 8, 2008, December 23, 2008 and January 5, 2009 (the &quot;Tender Offer&quot;).</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Doug Bailey</signatureName>
        <signatureDate>2009-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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