<SEC-DOCUMENT>0000898173-17-000121.txt : 20170512
<SEC-HEADER>0000898173-17-000121.hdr.sgml : 20170512
<ACCEPTANCE-DATETIME>20170512163018
ACCESSION NUMBER:		0000898173-17-000121
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170510
FILED AS OF DATE:		20170512
DATE AS OF CHANGE:		20170512

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			O REILLY AUTOMOTIVE INC
		CENTRAL INDEX KEY:			0000898173
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-AUTO & HOME SUPPLY STORES [5531]
		IRS NUMBER:				274358837
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802
		BUSINESS PHONE:		417-829-5878

	MAIL ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HENDRICKSON THOMAS
		CENTRAL INDEX KEY:			0001238978

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21318
		FILM NUMBER:		17839084

	MAIL ADDRESS:	
		STREET 1:		16234 SANDSTONE DRIVE
		CITY:			MORRISON
		STATE:			CO
		ZIP:			80465
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149462100373977.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-05-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000898173</issuerCik>
        <issuerName>O REILLY AUTOMOTIVE INC</issuerName>
        <issuerTradingSymbol>ORLY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001238978</rptOwnerCik>
            <rptOwnerName>HENDRICKSON THOMAS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1050 W HAMPDEN AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ENGLEWOOD</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80110</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>
            </securityTitle>
            <transactionDate>
                <value>2017-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>525</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>257.49</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4039</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents unvested restricted shares awarded under the Amended and Restated O'Reilly Automotive, Inc. 2003 Director's Stock Plan, which vest in three equal annual installments on May 10, 2018, 2019 and 2020.</footnote>
        <footnote id="F2">Total includes 1,027 unvested restricted shares awarded under the Amended and Restated O'Reilly Automotive, Inc. 2003 Director's Stock Plan and 3,012 shares held directly by Mr. Hendrickson.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Thomas T. Hendrickson</signatureName>
        <signatureDate>2017-05-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
