-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 laY1qBQv5FpsTorQbKdv9g==

<SEC-DOCUMENT>0000820318-08-000008.txt : 20080212
<SEC-HEADER>0000820318-08-000008.hdr.sgml : 20080212
<ACCEPTANCE-DATETIME>20080212131346
ACCESSION NUMBER:		0000820318-08-000008
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080209
FILED AS OF DATE:		20080212
DATE AS OF CHANGE:		20080212

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			II-VI INC
		CENTRAL INDEX KEY:			0000820318
		STANDARD INDUSTRIAL CLASSIFICATION:	OPTICAL INSTRUMENTS & LENSES [3827]
		IRS NUMBER:				251214948
		STATE OF INCORPORATION:			PA
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		375 SAXONBURG BLVD
		CITY:			SAXONBURG
		STATE:			PA
		ZIP:			16056
		BUSINESS PHONE:		724-352-4455

	MAIL ADDRESS:	
		STREET 1:		375 SAXONBURG BLVD
		CITY:			SAXONBURG
		STATE:			PA
		ZIP:			16056

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MORRISON DUNCAN A J
		CENTRAL INDEX KEY:			0001194654

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-16195
		FILM NUMBER:		08597043

	BUSINESS ADDRESS:	
		STREET 1:		II-VI INC
		STREET 2:		375 SAXONBURG BLVD.
		CITY:			SAXONBURG
		STATE:			PA
		ZIP:			16056
		BUSINESS PHONE:		(724) 352-4455

	MAIL ADDRESS:	
		STREET 1:		24824 DOWNIE LINE, RURAL ROUTE 4
		CITY:			WEST LORNE
		STATE:			A6
		ZIP:			N0L 2P0
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-02-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001194654</rptOwnerCik>
            <rptOwnerName>MORRISON DUNCAN A J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>24824 DOWNIE LINE, RURAL ROUTE 4</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WEST LORNE</rptOwnerCity>
            <rptOwnerState>A6</rptOwnerState>
            <rptOwnerZipCode>N0L 2P0</rptOwnerZipCode>
            <rptOwnerStateDescription>ONTARIO, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>30.83</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-02-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-02-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The option vests in 5 equal annual installments beginning on February 9, 2009.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michelle L. Freehling, Attorney-in-Fact</signatureName>
        <signatureDate>2008-02-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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