-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 NVOEfN1rIT2Lmf/0LMQaXa7p5CDwWyPmzG8Ytf9CwHM8d31MBb6WZ3ygQl+QgM0E
 hwuwFpR4NPXOMOtMLPxM0g==

<SEC-DOCUMENT>0001488150-10-000001.txt : 20100330
<SEC-HEADER>0001488150-10-000001.hdr.sgml : 20100330
<ACCEPTANCE-DATETIME>20100330210634
ACCESSION NUMBER:		0001488150-10-000001
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100330
FILED AS OF DATE:		20100330
DATE AS OF CHANGE:		20100330

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DEGUZMAN HERNAN
		CENTRAL INDEX KEY:			0001488150

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12718
		FILM NUMBER:		10715729

	MAIL ADDRESS:	
		STREET 1:		10 SAM CHUK STREET
		STREET 2:		SAN PO KONG, KOWLOON
		CITY:			HONG KONG
		STATE:			K3
		ZIP:			000000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SUPERTEX INC
		CENTRAL INDEX KEY:			0000730000
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				942328535
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1221

	BUSINESS ADDRESS:	
		STREET 1:		1235 BORDEAUX DR
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94089
		BUSINESS PHONE:		4087440100

	MAIL ADDRESS:	
		STREET 1:		1235 BORDEAUX DR
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94089
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2010-03-30</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000730000</issuerCik>
        <issuerName>SUPERTEX INC</issuerName>
        <issuerTradingSymbol>supx</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001488150</rptOwnerCik>
            <rptOwnerName>DEGUZMAN HERNAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10 SAM CHUK STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SAN PO KONG, KOWLOON</rptOwnerStreet2>
            <rptOwnerCity>HONG KONG</rptOwnerCity>
            <rptOwnerState>K3</rptOwnerState>
            <rptOwnerZipCode>000000</rptOwnerZipCode>
            <rptOwnerStateDescription>HONG KONG</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Asia Sales</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>ISO stock options (to exercise common stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>17.06</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-09-01</value>
            </exerciseDate>
            <expirationDate>
                <value>2011-09-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10750</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>NQ stock options (to exercise common stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>33.95</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2008-12-03</value>
            </exerciseDate>
            <expirationDate>
                <value>2017-12-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">ISO Option (to exercise common stock).  Exercise price: $17.06.  Shares granted: 20,000.  Shares exercised: 9,250.  Shares exercisable: 10,750.  Expiration date: 9/1/2011.  Held Direct.</footnote>
        <footnote id="F2">NQ Option (to exercise common stock).  Exercise price: $33.95.  Shares granted: 2,500.  Shares exercised: 0. Shares exercisable: 1,000.   500 shares exercisable 12/3/2010.  500 shares exercisable 12/3/2011. 500 shares exercisable 12/3/2012. Expiration date: 12/3/2017.  Held Direct.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Hernan DeGuzman</signatureName>
        <signatureDate>2010-03-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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