During a study of the Monogenea from some Australian native freshwater fishes found in south-east Queensland, a review of the literature was made to enumerate Australia's freshwater monogenean fauna. Twenty-six named species of Monogenea have been described from 16 species of native freshwater fishes. A further 16 records of monogeneans have been reported from native and introduced freshwater fishes, but these parasites await specific description. The only published record of a monogenean from an introduced species of freshwater fish in Australia is Gyrodactylus kobayashii Hukuda, 1940 from the goldfish Carassius auratus. An attempt is made to predict the biodiversity of the monogenean fauna of Australia's 180 species of freshwater fishes by applying a conservative estimate of three species of Monogenea per species of freshwater fish from a survey of relatively common freshwater fish species in subtropical south-east Queensland. This indicates that only 5% of an estimated 500 species of Monogenea have been described so far. An historical review of the study of the Monogenea from freshwater fishes in Australia and an updated parasite-host checklist is presented.