Fifteen enzymes and two blood proteins encoded by 24 presumptive loci were analyzed using starch-gel electrophoresis in 136 frogs of 16 populations of Rana ornativentris and 21 frogs of a sympatric population of Rana japonica, in order to elucidate the degree of geographic divergence of R. ornativentris in Honshu and its genetic relationships to R. japonica. The UPGMA dendrogram constructed from Nei's genetic distances showed that R. ornativentris from Honshu was divided into two distinct groups, western and eastern, and that the latter split into three subgroups, southern, central and northern. Genetic divergence was distinct between western and eastern populations of R. ornativentris at three loci, PEP-A, SOD-1 and Hb-1, with the Fst values of Wright of 0.624, 0.635 and 0.876, respectively. The average value of Fst (Fst), excluding the five invariant loci, was 0.306. Nei's genetic distances among the four western populations of R. ornativentris were 0.015∼0.061, 0.043 on average. Those among the 12 eastern populations were 0.011∼0.179, 0.063 on average, whereas those between the four western and 12 eastern populations were 0.128∼0.313, 0.225 on average. The genetic distances between the 16 populations of R. ornativentris and one population of R. japonica were 0.579∼0.956, 0.793 on average. The UPGMA dendrogram showed that R. ornativentris was distinctly separated from R. japonica.