<SEC-DOCUMENT>0000898173-18-000119.txt : 20180510
<SEC-HEADER>0000898173-18-000119.hdr.sgml : 20180510
<ACCEPTANCE-DATETIME>20180510163310
ACCESSION NUMBER:		0000898173-18-000119
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180509
FILED AS OF DATE:		20180510
DATE AS OF CHANGE:		20180510

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:		18823072

	MAIL ADDRESS:	
		STREET 1:		16234 SANDSTONE DRIVE
		CITY:			MORRISON
		STATE:			CO
		ZIP:			80465

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
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_152598437628888.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-09</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>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>2018-05-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>509</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>265.41</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4548</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 9, 2019, 2020 and 2021.</footnote>
        <footnote id="F2">Total includes 1,014 unvested restricted shares awarded under the Amended and Restated O'Reilly Automotive, Inc. 2003 Director's Stock Plan and 3,534 shares held directly by Mr. Hendrickson.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Thomas Hendrickson</signatureName>
        <signatureDate>2018-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
