A Guide to the Identification of Australian Freshwater Planktonic Chroococcales (Cyanoprokaryota / Cyanobacteria) aims to review the freshwater Australian species of the order Chroococcales (Cyanoprokaryota) that are known to be planktonic in lakes, reservoirs, rivers and streams, and present keys, morphological and ecological data, photomicrographs and original illustrations to facilitate the identification of the common genera and species. This guide by no means represents an exhaustive survey. Unfortunately, this is not possible at present as most laboratories from f^roughout Australia routinely analysing plankton samples rarely identify members of the Chroococcales to species level, with the exception of potentially toxic species, ie. Microcystis aeruginosa.