Marine leeches are sanguivorous parasites either on sea turtles (family Ozobranchidae) or on elasmobranch and teleost fishes (family Piscicolidae), with the exception of Mysidobdella, which may feed on mysid shrimp. The marine leeches of Australia and New Zealand are poorly known, especially those on teleost fishes. Collections of marine leeches from all major museums in Australia and New Zealand were examined, as well as many specimens sent to the author. Ozobranchus branchiatus and O. margoi were found on sea turtles in Australia. Seven genera and 14 species of fish leeches were found in Australia; 6 genera and 10 species of fish leeches were found in New Zealand. Two genera (Pontobdella and Branchellion) and four species (P. leucothela, P. moorei, B. australis and B. plicobranchus) occur in both Australia and New Zealand. No genus is endemic to Australia, but four species are endemic based on current records (Austrobdella bilobata, Austrobdella translucens, Trachelobdella leptocephali and Pterobdella platycephalus). Two genera (Bdellamaris and Leporinabdella) and three species (B. manteri, B. eptatreti, and L. digglesi) are endemic to New Zealand based on current records. The marine leeches of Australia and New Zealand are a mix of endemic species, those of tropical or subtropical origin, and those of subantarctic origin.