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

    <documentType>3</documentType>
  <periodOfReport>2003-09-08</periodOfReport>
    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001043533</issuerCik>
        <issuerName>ABOVENET INC</issuerName>
        <issuerTradingSymbol>NONE</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001209170</rptOwnerCik>
            <rptOwnerName>EMBLER MICHAEL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ABOVENET, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>360 HAMILTON AVENUE</rptOwnerStreet2>
            <rptOwnerCity>WHITE PLAINS</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10601</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
      <isDirector>1</isDirector>
      <isOfficer>0</isOfficer>
      <isTenPercentOwner>0</isTenPercentOwner>
      <isOther>0</isOther>
    </reportingOwnerRelationship>
  </reportingOwner>
  <ownerSignature>
    <signatureName>/s/ Michael Embler</signatureName>
    <signatureDate>2003-09-17</signatureDate>
  </ownerSignature>
</ownershipDocument>

