<SEC-DOCUMENT>0001140361-13-027919.txt : 20130711
<SEC-HEADER>0001140361-13-027919.hdr.sgml : 20130711
<ACCEPTANCE-DATETIME>20130711144958
ACCESSION NUMBER:		0001140361-13-027919
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20130711
FILED AS OF DATE:		20130711
DATE AS OF CHANGE:		20130711

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MANNATECH INC
		CENTRAL INDEX KEY:			0001056358
		STANDARD INDUSTRIAL CLASSIFICATION:	MEDICINAL CHEMICALS & BOTANICAL PRODUCTS [2833]
		IRS NUMBER:				752508900
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		600 SOUTH ROYAL LANE
		STREET 2:		SUITE 200
		CITY:			COPPELL
		STATE:			TX
		ZIP:			75019
		BUSINESS PHONE:		9724717400

	MAIL ADDRESS:	
		STREET 1:		600 SOUTH ROYAL LANE
		STREET 2:		SUITE 200
		CITY:			COPPELL
		STATE:			TX
		ZIP:			75019

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SINNOTT ROBERT A
		CENTRAL INDEX KEY:			0001298819

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24657
		FILM NUMBER:		13963796

	MAIL ADDRESS:	
		STREET 1:		400 55 WATER STREET
		CITY:			VANCOUVER
		STATE:			A1
		ZIP:			V6B1A1
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-07-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001056358</issuerCik>
        <issuerName>MANNATECH INC</issuerName>
        <issuerTradingSymbol>MTEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001298819</rptOwnerCik>
            <rptOwnerName>SINNOTT ROBERT A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 S. ROYAL LANE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>COPPELL</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO &amp; CSO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, Par Value $0.0001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-07-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1050</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.452</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2375</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By wife as custodian for sons</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This transaction involved a purchase of securities by the reporting person for the accounts of his three sons, all three of whom share the reporting person's household. The securities are owned by the reporting person's wife as custodian for his sons. The reporting person disclaims beneficial ownership of these shares, and this report shall not be deemed an admission that the reporting person is the beneficial owner of these shares for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F2">The price reported in Column 4 is a weighted average price.  These shares were purchased in multiple transactions at prices ranging from $11.410 to $11.459, inclusive.  The reporting person undertakes to provide Mannatech, Incorporated, any security holder of Mannatech, Incorporated, 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 this Form 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ S. Mark Nicholls Chief Financial Officer, by Power of Attorney</signatureName>
        <signatureDate>2013-07-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
