AbstractAllozyme variation was studied the three living species ofLeiopelma. L. hamiltoniandL. archeyiare shown to be closely related to each other althoughL. hamiltoniis slightly more divergent relative toL. hochstetteri. This parallels previous cytoenetic data. The rarity and insularity ofL. hamiltonienables the calculation of a mutation rate based on genetic variance and population size. A mutation rate per generation of 2.7times 10‐‐6is sufficient to account for the observed levels of variation. Six populations ofL. hochstetterishow a pattern of genetic divergence that also closely parallels previously detected cytogenetic variation.L. hochstetteriis genetically distant from its congeneric species while all species ofLeiopelmaare at an extreme genetic distance fromAscaphus truei, the only other living amphicoelous fro At the limits of resolution of the allozme technique,Ascaphusclusters with the more morphologically advanced frogs,DiscogiossusandBombina, rather than withLeiopelma. Taken with other evidence, this supports recognition of two families, Leiopelmatidae anl Ascaphidae, withLeiopelmathe probable sister group of all other fr