A polyphasic study of four Stigonematales cyanobacteria from tropical Australia (Queensland) revealed production of the hepatotoxins microcystins (MC-LR, MC-LA, MC-LF, MC-FR and demethyl-MC-LR) by Fischerella sp. NQAIF311 isolated from a seasonal creek. Total microcystin content reached 43 μg g-1 dry weight. Phylogeny demonstrated high sequence similarities for 16S rRNA (99%), mcyE (97%) and mcyD (95%) genes with microcystin-producing Fischerella sp. CENA161 from Brazil. This is the first report of a cyanotoxin-producing Stigonematal in Australia.