Estuarine intertidal mud-flats are highly productive habitats and crucial breeding grounds for a diverse array of macrobenthic organisms. Macrobenthic community assemblages (macroinvertebrates) have been used in the past as bioindicators of ecosystem health. Port Curtis is a shallow, semi-enclosed estuarine system situated on the central coast of Queensland approximately 500 kilometres north of Brisbane. Changes in macrobenthic assemblages (community structure) were assessed by investigating abundance, species richness, diversity and species evenness in intertidal and sub-tidal benthos at four sites within Port Curtis (Fisherman's Wart, Flying Fox, Worthington Island & Black Swan) from 1995-2005. A total of 12113 organisms from 418 taxa were collected throughout the harbour. Molluscs, polychaetes, crustaceans and chordates accounted for more than 97% of the individuals found. Other less common taxa encountered included echinoderms, cnidarians, sipunculids, nemerteans, branchiopods and pycnogonids.