<SEC-DOCUMENT>0001127602-23-009266.txt : 20230307
<SEC-HEADER>0001127602-23-009266.hdr.sgml : 20230307
<ACCEPTANCE-DATETIME>20230307160548
ACCESSION NUMBER:		0001127602-23-009266
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20230306
FILED AS OF DATE:		20230307
DATE AS OF CHANGE:		20230307

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Jaw Ching
		CENTRAL INDEX KEY:			0001710875

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50633
		FILM NUMBER:		23712603

	MAIL ADDRESS:	
		STREET 1:		280 EAST GRAND AVENUE
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CYTOKINETICS INC
		CENTRAL INDEX KEY:			0001061983
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				943291317
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		350 OYSTER POINT BOULEVARD
		STREET 2:		.
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
		BUSINESS PHONE:		(650) 624-3000

	MAIL ADDRESS:	
		STREET 1:		350 OYSTER POINT BOULEVARD
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-03-06</periodOfReport>

    <issuer>
        <issuerCik>0001061983</issuerCik>
        <issuerName>CYTOKINETICS INC</issuerName>
        <issuerTradingSymbol>CYTK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001710875</rptOwnerCik>
            <rptOwnerName>Jaw Ching</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2>350 OYSTER POINT BLVD</rptOwnerStreet2>
            <rptOwnerCity>SOUTH SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94080</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>SVP Finance &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-03-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2403</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>39.13</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>57346</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person is reporting the withholding of shares of common stock to satisfy the reporting persons withholding obligations in connection with the vesting of Restricted Stock Units vested on March 6, 2023, and does not represent a sale by the reporting person.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John Faurescu, attorney-in-fact for Mr. Jaw</signatureName>
        <signatureDate>2023-03-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
