-----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,
 TXttFbH5nsYsLTx7SL65KXcdaojKPBxETa/yLSgtp/W+15i8S7g6MwYjDFXNygCg
 UjcRNufbhK1DUW3hJYD0Dg==

<SEC-DOCUMENT>0000921895-07-001178.txt : 20070529
<SEC-HEADER>0000921895-07-001178.hdr.sgml : 20070528
<ACCEPTANCE-DATETIME>20070529185114
ACCESSION NUMBER:		0000921895-07-001178
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070524
FILED AS OF DATE:		20070529
DATE AS OF CHANGE:		20070529

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ADAPTEC INC
		CENTRAL INDEX KEY:			0000709804
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER COMMUNICATIONS EQUIPMENT [3576]
		IRS NUMBER:				942748530
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		691 S MILPITAS BLVD
		STREET 2:		M/S25
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
		BUSINESS PHONE:		4089458600

	MAIL ADDRESS:	
		STREET 1:		691 SOUTH MILPITAS BLVD
		STREET 2:		M/S25
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			STEEL PARTNERS LLC
		CENTRAL INDEX KEY:			0001262861

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15071
		FILM NUMBER:		07885042

	BUSINESS ADDRESS:	
		STREET 1:		590 MADISON AVENUE, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		212-758-3232

	MAIL ADDRESS:	
		STREET 1:		590 MADISON AVENUE, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			STEEL PARTNERS II LP
		CENTRAL INDEX KEY:			0000915653

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15071
		FILM NUMBER:		07885043

	BUSINESS ADDRESS:	
		STREET 1:		590 MADISON AVENUE
		STREET 2:		32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		212-758-3232

	MAIL ADDRESS:	
		STREET 1:		590 MADISON AVENUE, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022

	FORMER NAME:	
		FORMER CONFORMED NAME:	STEEL PARTNERS II L P
		DATE OF NAME CHANGE:	19950627

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LICHTENSTEIN WARREN G
		CENTRAL INDEX KEY:			0001005784
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15071
		FILM NUMBER:		07885044

	BUSINESS ADDRESS:	
		STREET 1:		C/O STEEL PARTNERS L P
		STREET 2:		32ND FLOOR 590 MADISON AVENUE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		212-758-3232

	MAIL ADDRESS:	
		STREET 1:		C/O STEEL PARTNERS II L P
		STREET 2:		590 MADISON AVENUE, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>ste23.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-05-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000709804</issuerCik>
        <issuerName>ADAPTEC INC</issuerName>
        <issuerTradingSymbol>ADPT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000915653</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001262861</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001005784</rptOwnerCik>
            <rptOwnerName>LICHTENSTEIN WARREN G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.001 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2007-05-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>55528</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.7500</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13665919</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.001 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2007-05-25</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>974148</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.8198</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14640067</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is filed jointly by Warren G. Lichtenstein, Steel Partners, L.L.C. (&quot;Steel LLC&quot;) and Steel Partners II, L.P. (&quot;Steel LP&quot;). Mr. Lichtenstein and Steel LLC are deemed to be 10% owners of the Issuer and Steel LP is a 10% owner of the Issuer. The securities reported in this Form 4 are owned directly by Steel LP, and owned indirectly by Steel LLC by virtue of it being the general partner of Steel LP and by Mr. Lichtenstein by virtue of his position as the sole executive officer and managing member of Steel LLC. Steel LLC and Mr. Lichtenstein disclaim beneficial ownership of the shares owned by Steel LP except to the extent of their pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Steel Partners II, L.P., By: Steel Partners, L.L.C., General Partner, By: /s/ Lauren Isenman, as Attorney in Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2007-05-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: Steel Partners, L.L.C., By: /s/ Lauren Isenman, as Attorney in Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2007-05-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ Lauren Isenman, as Attorney in Fact for Warren G. Lichtenstein</signatureName>
        <signatureDate>2007-05-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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