<SEC-DOCUMENT>0001415889-21-003774.txt : 20210803
<SEC-HEADER>0001415889-21-003774.hdr.sgml : 20210803
<ACCEPTANCE-DATETIME>20210803184421
ACCESSION NUMBER:		0001415889-21-003774
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210801
FILED AS OF DATE:		20210803
DATE AS OF CHANGE:		20210803

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MICHAELS KIMON
		CENTRAL INDEX KEY:			0001165534

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31311
		FILM NUMBER:		211141587

	MAIL ADDRESS:	
		STREET 1:		333 WEST SAN CARLOS STREET, SUITE 700
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PDF SOLUTIONS INC
		CENTRAL INDEX KEY:			0001120914
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				251701361
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2858 DE LA CRUZ BOULEVARD
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95050
		BUSINESS PHONE:		4082807900

	MAIL ADDRESS:	
		STREET 1:		2858 DE LA CRUZ BOULEVARD
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95050
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4-08032021_030812.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-01</periodOfReport>

    <issuer>
        <issuerCik>0001120914</issuerCik>
        <issuerName>PDF SOLUTIONS INC</issuerName>
        <issuerTradingSymbol>PDFS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001165534</rptOwnerCik>
            <rptOwnerName>MICHAELS KIMON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2858 DE LA CRUZ BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA CLARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95050</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>EVP OF PRODUCTS AND SOLUTIONS</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>21</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.71</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>118639</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1466959</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This represents a disposition of shares to the Company to satisfy tax withholding obligations with respect to the vesting of restricted stock units. This is not a sale of shares in the market.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kimon Michaels</signatureName>
        <signatureDate>2021-08-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
