<SUBMISSION>
<ACCESSION-NUMBER>0000820318-09-000011
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090223
<FILING-DATE>20090424
<DATE-OF-FILING-DATE-CHANGE>20090424
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>JOHNSON CARL J
<CIK>0000945117
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>000-16195
<FILM-NUMBER>09769062
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O II-VI INCORPORATED
<STREET2>375 SAXONBURG BLVD
<CITY>SAXONBURG
<STATE>PA
<ZIP>16056
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>II-VI INC
<CIK>0000820318
<ASSIGNED-SIC>3827
<IRS-NUMBER>251214948
<STATE-OF-INCORPORATION>PA
<FISCAL-YEAR-END>0630
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>375 SAXONBURG BLVD
<CITY>SAXONBURG
<STATE>PA
<ZIP>16056
<PHONE>724-352-4455
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>375 SAXONBURG BLVD
<CITY>SAXONBURG
<STATE>PA
<ZIP>16056
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2009-02-23</periodOfReport>

    <dateOfOriginalSubmission>2009-02-23</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000820318</issuerCik>
        <issuerName>II-VI INC</issuerName>
        <issuerTradingSymbol>IIVI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000945117</rptOwnerCik>
            <rptOwnerName>JOHNSON CARL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>503 APPLEHILL COURT</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GIBSONIA</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>15044</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2009-02-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>800</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>755064</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Spouse</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This amended Form 4 is being filed to correct the transaction date and price of the disclosed acquisition, which prevoiously had been reported incorrectly.</footnote>
        <footnote id="F2">The reporting person disclaims beneficial ownership of shares owned by his spouse.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michelle L. Freehling, Attorney-in-Fact</signatureName>
        <signatureDate>2009-04-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
