The collection of Cossuridae at the Australian Museum was investigated. Nine species were identified. Most specimens were from New South Wales and Queensland, but some specimens were also from Victoria, New Zealand, Fiji, Borneo, and the Philippines. Three new species were described: Cossura hutchingsae n.sp., C. keablei n.sp., and C. queenslandensis n.sp. Cossura consimilis Read, 2000 was redescribed using non-type material. Cossura aciculata (Wu & Chen, 1977) was identified from the coast of Borneo and the Philippines for the first time, and intraspecific variability in the number of thoracic chaetigers noted for that species. Three species, C. cf. ginesi, C. cf. longocirrata and C. cf. pygodactylata, were found to be morphologically similar to C. ginesi, C. longocirrata, and C. pygodactylata, respectively, but probably represent new species as they were found far from the known areas of the listed species. A key of the known cossurid species of Australian and adjacent waters is given, and taxonomical characteristics of Cossuridae are discussed.