The Australian species classified in the cosmopolitan genus Scymnus are revised. Nomenclatural history, diagnoses, illustrations and distribution are provided for each of the eleven recognized species. Scymnus fuscatus Boheman, 1859 is recorded from Australia for the first time. Four new species, Scymnus alligator, S. bunya, S. leai and S. tasmanicus are described. Lectotypes are designated for: Midus pygmaeus Blackburn, 1892, Scymnomorpha duplopunctulata Blackburn, 1892, Scymnus ambulans Blackburn, 1895, S. mitior Blackburn, 1895, S. parallelus Blackburn, 1889, S. queenslandicus Blackburn, 1892 and S. varipes Blackburn, 1895. A new name Scymnus blackburni nom. nov. is introduced for Scymnus pygmaeus (Blackburn, 1892) preoccupied by Scymnus pygmaeus (Fourcroy, 1785). Scymnus varipes Blackburn, 1895 is recognised as a junior synonym of Scymnus ambulans Blackburn, 1895 (syn. nov.)