A total of 17 species from the families Styelidae, Polyclinidae, Polycitoridae, Pseudodistomidae, Ritterellidae and Didemnidae are described for the first time in collections from remote fiords with steep-sided walls, high rainfall and high tidal flow on the south-west coast of New Zealand. The Fiordland ascidian assemblages are composed of endemic species, species with trans-Tasman affinities, species found in southern New Zealand and species found New Zealand wide, some of which have global distributions. Two Australian native species,Diplosoma velatumKott, 2001 and Didemnum jucundum Kott, 2001 from South Australia are new records to New Zealand and a further eight species remain undescribed. Two new colonial ascidians Aplidium coronum sp. nov. and Trididemnum shawi sp. nov. are described in this paper.