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

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-09-11</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000275694</issuerCik>
        <issuerName>MASSMUTUAL CORPORATE INVESTORS</issuerName>
        <issuerTradingSymbol>MCI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001448864</rptOwnerCik>
            <rptOwnerName>Walsh Patricia J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BABSON CAPITAL MANAGEMENT LLC</rptOwnerStreet1>
            <rptOwnerStreet2>1500 MAIN STREET  PO BOX 15189</rptOwnerStreet2>
            <rptOwnerCity>SPRINGFIELD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01115</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle>VP, Officer of Adviser</officerTitle>
            <otherText>VP, Officer of Adviser</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>By: Ann Malloy as Attorney-in-fact for</signatureName>
        <signatureDate>2008-11-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
