Occasional Reports of the Australian Museum no. 3. Preface: The Australian Museum received funding from FIRTA to undertake a baseline survey of Twofold Bay, New South Wales one of the ports where Japanese ships regularly discharge ballast water. Twofold Bay was one of the Bays previously identified as receiving ballast water containing live organisms and there was considerable concern as to whether any of these organisms had become established in the Bay and could potentially become pests. While undertaking this baseline survey it became apparent that a major review of the potential problems of discharging large quantities of ballast water into Australian ports needed to be undertaken. This review was subsequently undertaken together with a summary of all the reported marine introductions into Australian waters. FIRTA provided additional funds to ensure that this review was freely available as an Occasional Reports Series (No. 3) of the Australian Museum.