<SEC-DOCUMENT>0000856982-19-000022.txt : 20190305
<SEC-HEADER>0000856982-19-000022.hdr.sgml : 20190305
<ACCEPTANCE-DATETIME>20190305183929
ACCESSION NUMBER:		0000856982-19-000022
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190301
FILED AS OF DATE:		20190305
DATE AS OF CHANGE:		20190305

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Wright Joseph
		CENTRAL INDEX KEY:			0001643713

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-18592
		FILM NUMBER:		19660464

	MAIL ADDRESS:	
		STREET 1:		1600 WEST MERIT PARKWAY
		CITY:			SOUTH JORDAN
		STATE:			UT
		ZIP:			84095

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MERIT MEDICAL SYSTEMS INC
		CENTRAL INDEX KEY:			0000856982
		STANDARD INDUSTRIAL CLASSIFICATION:	SURGICAL & MEDICAL INSTRUMENTS & APPARATUS [3841]
		IRS NUMBER:				870447695
		STATE OF INCORPORATION:			UT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1600 WEST MERIT PARK WAY
		CITY:			SOUTH JORDAN
		STATE:			UT
		ZIP:			84095
		BUSINESS PHONE:		8012531600

	MAIL ADDRESS:	
		STREET 1:		1600 WEST MERIT PARKWAY
		CITY:			SOUTH JORDAN
		STATE:			UT
		ZIP:			84095
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_155182915512144.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-03-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000856982</issuerCik>
        <issuerName>MERIT MEDICAL SYSTEMS INC</issuerName>
        <issuerTradingSymbol>MMSI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001643713</rptOwnerCik>
            <rptOwnerName>Wright Joseph</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1600 WEST MERIT PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUTH JORDAN</rptOwnerCity>
            <rptOwnerState>UT</rptOwnerState>
            <rptOwnerZipCode>84095</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, International</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.14</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2014-07-31</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-07-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.06</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2015-10-04</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-10-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>17.27</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2016-02-13</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-02-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.05</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-01-28</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-01-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>28.2</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2018-04-14</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-04-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>44.8</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2019-03-02</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-03-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-qualified stock options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>55.73</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-03-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2020-03-01</value>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-03-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Becomes exercisable in equal annual installments of 20% commencing on 07/31/2014.</footnote>
        <footnote id="F2">Becomes exercisable in equal annual installments of 20% commencing on 10/04/2015.</footnote>
        <footnote id="F3">Becomes exercisable in equal annual installments of 20% commencing on 02/13/2016.</footnote>
        <footnote id="F4">Becomes exercisable in equal annual installments of 20% commencing on 01/28/2017.</footnote>
        <footnote id="F5">Becomes exercisable in equal annual installments of 20% commencing on 04/14/2018.</footnote>
        <footnote id="F6">Becomes exercisable in equal annual installments of 20% commencing on 03/02/2019.</footnote>
        <footnote id="F7">Becomes exercisable in equal annual installments of 20% commencing on 03/01/2020.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Brian G. Lloyd, Attorney-in-Fact</signatureName>
        <signatureDate>2019-03-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
