<?xml version="1.0" encoding="utf-8"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
  <periodOfReport>2003-11-18</periodOfReport>
  <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001070698</issuerCik>
        <issuerName>AXONYX INC</issuerName>
        <issuerTradingSymbol>AXYX</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001250856</rptOwnerCik>
            <rptOwnerName>BRUINSMA GOSSE B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>500 SEVENTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>10TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10018</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
      <isDirector>1</isDirector>
      <isOfficer>1</isOfficer>
      <isTenPercentOwner>0</isTenPercentOwner>
      <isOther>0</isOther>
      <officerTitle>President &amp; Chief Operating Of</officerTitle>
    </reportingOwnerRelationship>
  </reportingOwner>
  <derivativeTable>
    <derivativeTransaction>
      <securityTitle>
        <value>Non-Statutory Stock Option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>3.61</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2003-11-18</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>100000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>3.61</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2003-11-18</value>
        <footnoteId id="F1"/>
      </exerciseDate>
      <expirationDate>
        <value>2013-11-17</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Common Stock</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>100000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>100000</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
  </derivativeTable>
  <footnotes>
    <footnote id="F1">These non-statutory stock options were granted on November 18, 2003 and the grant provides for vesting in four equal annual installments commencing with the vesting of 25,000 options on November 18, 2003.</footnote>
  </footnotes>
  <ownerSignature>
    <signatureName>/s/ Gosse B. Bruinsma, M.D.</signatureName>
    <signatureDate>2003-11-19</signatureDate>
  </ownerSignature>
</ownershipDocument>

