<SEC-DOCUMENT>0001628280-18-010230.txt : 20180801
<SEC-HEADER>0001628280-18-010230.hdr.sgml : 20180801
<ACCEPTANCE-DATETIME>20180801174835
ACCESSION NUMBER:		0001628280-18-010230
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180731
FILED AS OF DATE:		20180801
DATE AS OF CHANGE:		20180801

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CAPPS ROBERT P
		CENTRAL INDEX KEY:			0001233504

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13490
		FILM NUMBER:		18985956

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MITCHAM INDUSTRIES INC
		CENTRAL INDEX KEY:			0000926423
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-EQUIPMENT RENTAL & LEASING, NEC [7359]
		IRS NUMBER:				760210849
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			0131

	BUSINESS ADDRESS:	
		STREET 1:		8141 SH 75 SOUTH
		STREET 2:		PO BOX 1175
		CITY:			HUNTSVILLE
		STATE:			TX
		ZIP:			77342
		BUSINESS PHONE:		9362912277

	MAIL ADDRESS:	
		STREET 1:		P O BOX 1175
		CITY:			HUNTSVILLE
		STATE:			TX
		ZIP:			77342
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_153316009954027.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-07-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000926423</issuerCik>
        <issuerName>MITCHAM INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>MIND</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001233504</rptOwnerCik>
            <rptOwnerName>CAPPS ROBERT P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>8141 SH 75 SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HUNTSVILLE</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77342</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Co-CEO and CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>MII Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-07-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.99</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>41930</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported is an average price. These shares were purchased in multiple transactions at prices ranging from $3.89 to $4.00, inclusive. The reporting person undertakes to provide to Mitcham Industries, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (1) of this Form 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Robert P. Capps</signatureName>
        <signatureDate>2018-08-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
