<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2004-08-25</periodOfReport>

    <dateOfOriginalSubmission>2004-02-06</dateOfOriginalSubmission>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000914329</issuerCik>
        <issuerName>FEI CO</issuerName>
        <issuerTradingSymbol>FEIC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001263237</rptOwnerCik>
            <rptOwnerName>PHILIPS BUSINESS ELECTRONICS INTERNATIONAL BV</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GLASLAAN 2</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EINDHOVEN, THE NETHERLANDS</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode>5616 LW</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000313216</rptOwnerCik>
            <rptOwnerName>KONINKLIJKE PHILIPS ELECTRONICS NV</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GLASLAAN 2</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EINDHOVEN, THE NETHERLANDS</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode>5616 LW</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-08-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>14436</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8406007</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-12-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8406007</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to a Combination Agreement, dated November 15, 1996, as supplemented by an agreement effective as of December 31, 2000 (the &quot;Combination Agreement&quot;), by and among Philips Business Electronics International B.V. (&quot;PBE&quot;), Koninklijke Philips Electronics N.V. (&quot;Philips&quot;) and FEI Company (the &quot;Issuer&quot;), PBE has the right to receive from the Issuer, from time to time, without the payment of any additional consideration, additional shares of Common Stock when options, warrants, convertible securities or other rights to acquire shares of Common Stock outstanding (or issuable without further action by the Issuer's board of directors) as of February 21, 1997, are exercised or converted.  PBE is a wholly-owned subsidiary of Philips.  Accordingly, securities owned by PBE may be deemed beneficially owned by Philips.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ G.J. KLEISTERLEE, President &amp; CEO, KONINKLIJKE PHILIPS ELECTRONICS N.V.</signatureName>
        <signatureDate>2006-12-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ P.J. SIVIGNON, Executive Vice President &amp; CFO, KONINKLIJKE PHILIPS ELECTRONICS N.V.</signatureName>
        <signatureDate>2006-12-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ P.J. SIVIGNON, Authorised Person, PHILIPS BUSINESS ELECTRONICS INTERNATIONAL B.V.</signatureName>
        <signatureDate>2006-12-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
