Cyanobacterial samples were collected between April 1989 and May 1997 from six drainage divisions in coastal areas of Australia: the northeast coast, southeast coast, Tasmania, Murray–Darling Basin, South Australian coast and southwest coast. Saxitoxins were detected in approximately 70% of all field samples and 57% of cultured strains of Anabaena circinalis. Maximum saxitoxin concentrations were 4466 and 2553 μg g−1 dry weight cells in field samples and strains, respectively. Toxin profiles were similar in the majority of field samples and strains. The toxins were predominantly C-toxins (C1 and C2) and gonyautoxins (GTX2 and GTX3), with saxitoxin sensu stricto (STX), GTX5 and decarbamoyl gonyautoxins (dcGTX2 and dcGTX3) being present in minor amounts. A unique toxin composition (exclusively STX and GTX5) was found in a geographically isolated strain from the southwest coast of Australia. N1-hydroxy saxitoxins (neoSTX, GTX1 and GTX4) were not detected in any field sample or cultured strain. Anabaena circinalis may not be the only Anabaena species producing saxitoxins, as very low concentrations of GTX3 (14 μg g−1 dry weight cells or less) were detected in two other Anabaena species: A. perturbata var. tumida and A. spiroides. One decarbamoyl gonyautoxin (dcGTX3) was also present in one A. perturbata var. tumida strain. Anatoxin-a was not detected in Australian strains of Anabaena. Trace amounts of 0.23 and 0.10 μg microcystin-LR equivalents g−1 dry weight cells were found in two cultured strains of Anabaena cylindrica. An increase in toxin concentration from 0 to 4423 μg saxitoxins g−1 dry weight cells was observed over a 3-month period in a series of samples collected from a persistent bloom of A. circinalis at Wongulla Lagoon, South Australia. This temporal variation in saxitoxin concentrations is similar to that reported for microcystins in Microcystis aeruginosa (Chroococcales, Cyanophyta).