<SEC-DOCUMENT>0000914122-13-000024.txt : 20130528
<SEC-HEADER>0000914122-13-000024.hdr.sgml : 20130527
<ACCEPTANCE-DATETIME>20130528114215
ACCESSION NUMBER:		0000914122-13-000024
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20130430
FILED AS OF DATE:		20130528
DATE AS OF CHANGE:		20130528

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MILLER EUGENE
		CENTRAL INDEX KEY:			0001247464

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32530
		FILM NUMBER:		13874032

	MAIL ADDRESS:	
		STREET 1:		7720 N LEHIGH AVE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MFRI INC
		CENTRAL INDEX KEY:			0000914122
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL & COMMERCIAL FANS & BLOWERS & AIR PURIFYING EQUIP [3564]
		IRS NUMBER:				363922969
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0131

	BUSINESS ADDRESS:	
		STREET 1:		7720 LEHIGH AVE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714
		BUSINESS PHONE:		8479661000

	MAIL ADDRESS:	
		STREET 1:		7720 LEHIGH AVE
		CITY:			NILES
		STATE:			IL
		ZIP:			60714

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MIDWESCO FILTER RESOURCES INC
		DATE OF NAME CHANGE:	19970402
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-04-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000914122</issuerCik>
        <issuerName>MFRI INC</issuerName>
        <issuerTradingSymbol>MFRI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001247464</rptOwnerCik>
            <rptOwnerName>MILLER EUGENE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7720 N LEHIGH AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NILES</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60714</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>346</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>346</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>346</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">(1) Deferred Stock Units earned by the reporting person by elective deferral of director retainer, pursuant to the company's Deferred Stock Purchase Plan.  The Deferred Stock Units are payable to the reporting person in Common Stock on a one-for-one basis, upon separation of service as a member of the Board.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Eugene Miller</signatureName>
        <signatureDate>2013-05-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
