-----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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<SEC-DOCUMENT>0001044321-09-000003.txt : 20090109
<SEC-HEADER>0001044321-09-000003.hdr.sgml : 20090109
<ACCEPTANCE-DATETIME>20090109103001
ACCESSION NUMBER:		0001044321-09-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090107
FILED AS OF DATE:		20090109
DATE AS OF CHANGE:		20090109

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FSI INTERNATIONAL INC
		CENTRAL INDEX KEY:			0000841692
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY, NEC [3559]
		IRS NUMBER:				411223238
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			0831

	BUSINESS ADDRESS:	
		STREET 1:		3455 LYMAN BLVD.
		CITY:			CHASKA
		STATE:			MN
		ZIP:			55318
		BUSINESS PHONE:		9524485440

	MAIL ADDRESS:	
		STREET 1:		3455 LYMAN BLVD.
		CITY:			CHASKA
		STATE:			MN
		ZIP:			55318

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MARXE AUSTIN W & GREENHOUSE DAVID M
		CENTRAL INDEX KEY:			0001044321

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-17276
		FILM NUMBER:		09517291

	BUSINESS ADDRESS:	
		STREET 1:		C/O SPECIAL SITUATIONS FUNDS
		STREET 2:		527 MADISON AVENUE, SUITE 2600
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		2122076500

	MAIL ADDRESS:	
		STREET 1:		C/O SPECIAL SITUATIONS FUNDS
		STREET 2:		527 MADISON AVENUE, SUITE 2600
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-01-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000841692</issuerCik>
        <issuerName>FSI INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>FSI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001044321</rptOwnerCik>
            <rptOwnerName>MARXE AUSTIN W &amp; GREENHOUSE DAVID M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SPECIAL SITUATIONS FUNDS</rptOwnerStreet1>
            <rptOwnerStreet2>527 MADISON AVENUE, SUITE 2600</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-01-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>95525</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.33</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3670071</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Limited Partnerships</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-01-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.333</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3700071</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Limited Partnerships</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-01-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20300</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.36</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3720371</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Limited Partnerships</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This is a joint filing by Austin W. Marxe (Marxe) and David M. Greenhouse (Greenhouse).  They share voting and investment control over all securities owned by Special Situations Fund III QP, LP (QP) and Special Situations Cayman Fund, L.P. (Cayman), respectively.  2,838,341 shares of Common Stock are held by QP and 882,030 shares of Common Stock are held by Cayman.  The interest of Marxe and Greenhouse in the shares of Common Stock owned by QP and Cayman is limited to the extent of his pecuniary interest.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Austin W. Marxe</signatureName>
        <signatureDate>2009-01-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David M. Greenhouse</signatureName>
        <signatureDate>2009-01-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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