<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-10-17</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001138723</issuerCik>
        <issuerName>ACCURAY INC</issuerName>
        <issuerTradingSymbol>ARAY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001756775</rptOwnerCik>
            <rptOwnerName>Chew Jesse</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1310 CHESAPEAKE TERRACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SUNNYVALE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94089</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP and General Counsel</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37064</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">9,204 shares are held directly by the reporting person, of which 5,510 of these shares were acquired through the Accuray 2007 Employee Stock Purchase Plan. The remaining 3,694 shared directly owned were acquired through the vesting and release of RSUs. Also included in this total are 1,075 remaining unvested RSUs granted on 10/31/2014; 2,000 remaining unvested RSUs granted on 10/30/2015; 4,785 remaining unvested RSUs granted on 10/31/2016; 20,000 shares remaining unvested RSUs granted on 10/31/2017 which vests 25% annually over 4 years.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: John McKune  For: Jesse Chew</signatureName>
        <signatureDate>2018-10-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
