<SEC-DOCUMENT>0000898173-17-000124.txt : 20170512
<SEC-HEADER>0000898173-17-000124.hdr.sgml : 20170512
<ACCEPTANCE-DATETIME>20170512163300
ACCESSION NUMBER:		0000898173-17-000124
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:			RASHKOW RONALD
		CENTRAL INDEX KEY:			0001226499

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21318
		FILM NUMBER:		17839167

	MAIL ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149462116620860.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>0001226499</rptOwnerCik>
            <rptOwnerName>RASHKOW RONALD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>233 S. PATTERSON AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPRINGFIELD</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>65802</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>6030</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 5,003 shares held directly by Mr. Rashkow.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Ronald Rashkow</signatureName>
        <signatureDate>2017-05-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
