The labroid fish family Odacidae consists of 12 species found in the shallow, temperate waters of Australia and New Zealand. A study of external and osteological features revealed 11 derived characters that occur rarely, if at all, in other labroid fishes. The distribution of 29 other characters indicates phylogenetic relationships that support the recognition of 4 genera. Two genera, Neoodax (N. balteatus) and Haletta (H. semifasciata) are monotypic and restricted to Australian waters. A third, Odax, includes the 2 New Zealand species, O. cyanoallix and O. pullus, and 2 Australian species, O. acroptilus and O. cyanomelas. The fourth genus, Siphonognathus, comprises 6 species (S. argyrophanes, S. attenuatus, S. beddomei, S. caninus, S. radiatus, and a new species S. tanyourus), all restricted to the southern and temperate western coasts of Australia. Descriptions of S. tanyourus and the 11 other species of the family are presented.