<SEC-DOCUMENT>0000866273-15-000104.txt : 20151113
<SEC-HEADER>0000866273-15-000104.hdr.sgml : 20151113
<ACCEPTANCE-DATETIME>20151113151302
ACCESSION NUMBER:		0000866273-15-000104
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20151112
FILED AS OF DATE:		20151113
DATE AS OF CHANGE:		20151113

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MATRIX SERVICE CO
		CENTRAL INDEX KEY:			0000866273
		STANDARD INDUSTRIAL CLASSIFICATION:	CONSTRUCTION SPECIAL TRADE CONTRACTORS [1700]
		IRS NUMBER:				731352174
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		5100 EAST SKELLY DRIVE
		STREET 2:		SUITE 700
		CITY:			TULSA
		STATE:			OK
		ZIP:			74135
		BUSINESS PHONE:		9188388822

	MAIL ADDRESS:	
		STREET 1:		5100 EAST SKELLY DRIVE
		STREET 2:		SUITE 700
		CITY:			TULSA
		STATE:			OK
		ZIP:			74135

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HENDRIX I EDGAR
		CENTRAL INDEX KEY:			0001183495
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0531

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15461
		FILM NUMBER:		151228804

	MAIL ADDRESS:	
		STREET 1:		413 W. CHARLOTTE
		CITY:			BROKEN ARROW
		STATE:			OK
		ZIP:			74011

	FORMER NAME:	
		FORMER CONFORMED NAME:	HENDRIX J EDGAR
		DATE OF NAME CHANGE:	20020828
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_144744557246966.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-11-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000866273</issuerCik>
        <issuerName>MATRIX SERVICE CO</issuerName>
        <issuerTradingSymbol>MTRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183495</rptOwnerCik>
            <rptOwnerName>HENDRIX I EDGAR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5100 EAST SKELLY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 700</rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74135</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2015-11-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3661</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37090</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">MATRIX SERVICE COMPANY COMMON STOCK.</footnote>
        <footnote id="F2">RESTRICTED STOCK UNIT - EACH UNIT WILL ENTITLE THE REPORTING PERSON TO ONE SHARE OF MATRIX SERVICE COMPANY COMMON STOCK IF AND WHEN THE CONDITIONS OF THE RESTRICTION HAVE BEEN SATISFIED.  FOR THIS GRANT, 100% WILL VEST ON THE THIRD ANNIVERSARY DATE.</footnote>
        <footnote id="F3">NOT APPLICABLE.</footnote>
        <footnote id="F4">INCLUDES 18,000 SHARES OF MATRIX SERVICE COMPANY COMMON STOCK OWNED OUTRIGHT.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>I. Edgar Hendrix</signatureName>
        <signatureDate>2015-11-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
