<?xml version="1.0"?>
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    <periodOfReport>2016-09-20</periodOfReport>

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    <issuer>
        <issuerCik>0000100493</issuerCik>
        <issuerName>TYSON FOODS INC</issuerName>
        <issuerTradingSymbol>TSN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001552992</rptOwnerCik>
            <rptOwnerName>Hayes Thomas P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2200 W DON TYSON PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPRINGDALE</rptOwnerCity>
            <rptOwnerState>AR</rptOwnerState>
            <rptOwnerZipCode>72762</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <transactionDate>
                <value>2016-11-28</value>
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                    <value>A</value>
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                <value>2017-11-28</value>
            </exerciseDate>
            <expirationDate>
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            <underlyingSecurity>
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                </underlyingSecurityTitle>
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                <footnoteId id="F6"/>
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                    <value>Class A Common Stock</value>
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                </directOrIndirectOwnership>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares of the Issuer's Class A Common Stock received by the Reporting Person pursuant to the Issuer's dividend reinvestment plan since the last Statement of Changes in Beneficial Ownership was filed by the Reporting Person.  Such acquisitions are exempt from Section 16 concurrent reporting requirements pursuant to Rule 16a-11.</footnote>
        <footnote id="F2">Includes 7,840.583 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 47,142.996 shares of Class A Common Stock which vest on July 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; and 8,513.437 shares of Class A Common Stock which vest on December 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved.</footnote>
        <footnote id="F3">Award of Class A Common Stock which vests on November 18, 2019 if the performance metric described in the applicable Stock Incentive Agreement is achieved. The performance metric is the achievement of a three year (fiscal 2017-2019) cumulative EBIT target as set forth in the Stock Incentive Agreement. If the performance metric is not achieved, the award expires.</footnote>
        <footnote id="F4">Includes 7,840.583 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 47,142.996 shares of Class A Common Stock which vest on July 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 8,513.437 shares of Class A Common Stock which vest on December 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; and 20,354.817 shares of Class A Common Stock which vest on November 18, 2019 if the performance metric described in the applicable Stock Incentive Agreement is achieved.</footnote>
        <footnote id="F5">The stock options vest at 33 1/3% on each of the first, second, and third anniversary dates of the grant.</footnote>
        <footnote id="F6">Award of performance Class A Common Stock which vests on November 18, 2019 if the performance metrics described in the applicable Stock Incentive Agreement are achieved. The performance metrics set forth in the Stock Incentive Agreement are (1) achievement of a three year (fiscal 2017-2019) cumulative EBIT target and (2) a favorable comparison of the relative total shareholder return of the Issuer's Class A Common Stock compared to a predetermined peer group of publicly traded companies over a three year (fiscal 2017-2019) period. Subject to the achievement of the performance metrics, the performance shares could vest at a level of 50%-200% and are reported as derivative securities at the 200% level. If neither of the performance metrics are achieved, the award expires.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ R. Read Hudson by Power of Attorney for Thomas P. Hayes</signatureName>
        <signatureDate>2016-11-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2016-09-20
0
0000100493
TYSON FOODS INC
TSN
0001552992
Hayes Thomas P
2200 W DON TYSON PARKWAY
SPRINGDALE
AR
72762
1
1
0
0
President
Class A Common Stock
2016-09-20
4
J
0
603.8527
0
A
63497.016
D
Class A Common Stock
2016-11-28
4
A
0
20354.817
0
A
83851.833
D
Non-Qualified Stock Options (Right to Buy)
58.34
2016-11-28
4
A
0
88488
58.34
A
2017-11-28
2026-11-28
Class A Common Stock
88488.0
88488
D
Performance Shares
2016-11-28
4
A
0
81419.266
A
Class A Common Stock
81419.266
81419.266
D
Represents shares of the Issuer's Class A Common Stock received by the Reporting Person pursuant to the Issuer's dividend reinvestment plan since the last Statement of Changes in Beneficial Ownership was filed by the Reporting Person.  Such acquisitions are exempt from Section 16 concurrent reporting requirements pursuant to Rule 16a-11.
Includes 7,840.583 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 47,142.996 shares of Class A Common Stock which vest on July 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; and 8,513.437 shares of Class A Common Stock which vest on December 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved.
Award of Class A Common Stock which vests on November 18, 2019 if the performance metric described in the applicable Stock Incentive Agreement is achieved. The performance metric is the achievement of a three year (fiscal 2017-2019) cumulative EBIT target as set forth in the Stock Incentive Agreement. If the performance metric is not achieved, the award expires.
Includes 7,840.583 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 47,142.996 shares of Class A Common Stock which vest on July 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; 8,513.437 shares of Class A Common Stock which vest on December 1, 2018 if the performance metrics described in the applicable Stock Incentive Agreement are achieved; and 20,354.817 shares of Class A Common Stock which vest on November 18, 2019 if the performance metric described in the applicable Stock Incentive Agreement is achieved.
The stock options vest at 33 1/3% on each of the first, second, and third anniversary dates of the grant.
Award of performance Class A Common Stock which vests on November 18, 2019 if the performance metrics described in the applicable Stock Incentive Agreement are achieved. The performance metrics set forth in the Stock Incentive Agreement are (1) achievement of a three year (fiscal 2017-2019) cumulative EBIT target and (2) a favorable comparison of the relative total shareholder return of the Issuer's Class A Common Stock compared to a predetermined peer group of publicly traded companies over a three year (fiscal 2017-2019) period. Subject to the achievement of the performance metrics, the performance shares could vest at a level of 50%-200% and are reported as derivative securities at the 200% level. If neither of the performance metrics are achieved, the award expires.
/s/ R. Read Hudson by Power of Attorney for Thomas P. Hayes
2016-11-30