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

    <schemaVersion>X0101</schemaVersion>

    <submissionType>EFFECT</submissionType>

    <act>33</act>

    <testOrLive>LIVE</testOrLive>

    <effectiveData>
        <finalEffectivenessDispDate>2008-11-21</finalEffectivenessDispDate>
        <finalEffectivenessDispTime>12:00:00</finalEffectivenessDispTime>
        <form>S-4</form>
        <filer>
            <cik>0000356830</cik>
            <entityName>OSCIENT PHARMACEUTICALS CORP</entityName>
            <fileNumber>333-153394</fileNumber>
        </filer>
        <filer>
            <cik>0001443593</cik>
            <entityName>Guardian II Acquisition CORP</entityName>
            <fileNumber>333-153394-01</fileNumber>
        </filer>
    </effectiveData>
</edgarSubmission>
