<SEC-DOCUMENT>0000866273-16-000292.txt : 20161222
<SEC-HEADER>0000866273-16-000292.hdr.sgml : 20161222
<ACCEPTANCE-DATETIME>20161222184057
ACCESSION NUMBER:		0000866273-16-000292
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20161222
FILED AS OF DATE:		20161222
DATE AS OF CHANGE:		20161222

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:			Rinehart Bradley J
		CENTRAL INDEX KEY:			0001183498
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0531

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15461
		FILM NUMBER:		162067717

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

	FORMER NAME:	
		FORMER CONFORMED NAME:	RINEHART BRAD J
		DATE OF NAME CHANGE:	20020828
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_148245004376267.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-12-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183498</rptOwnerCik>
            <rptOwnerName>Rinehart Bradley J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5100 EAST SKELLY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 500</rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74135</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, Matrix PDM Eng</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8072</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.7047</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>76535</value>
                    <footnoteId id="F3"/>
                </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">THE PRICE REPORTED IS A WEIGHTED AVERAGE PRICE.  THESE SHARES WERE SOLD IN MULTIPLE TRANSACTIONS AT PRICES RANGING FROM $22.70 TO $22.75, INCLUSIVE.  THE REPORTING PERSON UNDERTAKES TO PROVIDE TO MATRIX SERVICE COMPANY, ANY SECURITY HOLDER OF MATRIX SERVICE COMPANY, OR THE STAFF OF THE SECURITIES AND EXCHANGE COMMISSION, UPON REQUEST, FULL INFORMATION REGARDING THE NUMBER OF SHARES SOLD AT EACH SEPARATE PRICE WITHIN THE RANGE SET FORTH.</footnote>
        <footnote id="F3">INCLUDES 59,562 SHARES OF MATRIX SERVICE COMPANY COMMON STOCK OWNED OUTRIGHT.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Bradley J. Rinehart</signatureName>
        <signatureDate>2016-12-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
