The crab spiders of the genus Diaea from Australia are revised. All the known 30 species are redescribed and illustrated. The type species of the genus — Diaea dorsata (Fabricius, 1777) (distributed in Palaearctic) is also included into this study. All the former members of Diaea from Australia changed their taxonomic position as a result of transfer to other genera. Three new genera were established: Australomisidia gen. nov., Boomerangia gen. nov. and Lehtinelagia gen. nov. Twenty new combinations are proposed: Australomisidia cruentata (L. Koch, 1874), A. elegans (L. Koch, 1876), A. ergandros (Evans, 1995), A. inornata (L. Koch, 1876), A. kangarooblaszaki (Szymkowiak, 2008), A. pilula (L. Koch, 1867), A. rosea (L. Koch, 1875), A. socialis (Main, 1988), Boomerangia dimidiata (L. Koch, 1867), Cetratus caecutiens (L. Koch, 1876), C. circumlitus (L. Koch, 1876), C. rubropunctatus (Rainbow, 1920), C. tenuis (L. Koch, 1875), Lehtinelagia evanida (L. Koch, 1876), L. multopunctata (L. Koch, 1874), L. prasina (L. Koch, 1876), L. pulleinei (Rainbow, 1915), L. variabilis (L. Koch, 1875), Runcinia insecta (L. Koch, 1875), Zygometis xanthogaster (L. Koch, 1875). Four species are regarded as nomina dubia: D. mollis L. Koch, 1875, Diaea olivacea L. Koch, 1875, D. plumbea L. Koch, 1875, D. punctipes L. Koch, 1875. Following specific names are synonymised: Diaea blanda L. Koch, 1875 with Australomisidia pilula, Diaea haematodactyla L. Koch, 1875 with Lehtinelagia evanida, Diaea jucunda Thorell, 1881 with Mastira adusta (L. Koch, 1867), Diaea multimaculata Rainbow, 1904, Diaea punctata L. Koch, 1875 with Lehtinelagia multopunctata, Diaea velata L. Koch, 1876 with Boomerangia dimidiata, Misumena tristania Rainbow, 1900, M. lactea L. Koch, 1876 with Diaea xanthogaster L. Koch, 1875 (and transferred to the genus Zygometis), Runcinia affinis Simon, 1897 with Diaea insecta L. Koch, 1875 (placed into Runcinia) and Xysticus bilimbatus