Electrophoretic patterns of 14 enzymes and four blood proteins were examined in 261 frogs of 13 populations belonging to three Hyla species, H. japonica, H. hallowelli and H. chinensis. It was found that these enzymes and blood proteins were controlled by genes at 26 loci. The numbers of alleles and phenotypes at the 26 loci were one to nine, 4.0 on the average, and one to 17,6.1 on the average, respectively. The mean proportions of heterozygous and polymorphic loci and mean number of alleles per locus in the 13 populations were 11.7%, 37.3 0x0p+0nd 1.47 on the average, respectively. The genetic distances among the 13 populations of the three Hyla species were estimated on the basis of gene frequencies at the 26 loci by the method of NEI (1975). Those among the 11 populations of Sakhalin, Kunashiri, Sapporo, Setana, Hirosaki, Ichinoseki, Odawara, Maibara, Hiroshima, Tsushima and Korea of H. japonica were 0.012∿0.201. Those between the Tsushima and the other 10 populations of H. japonica were 0.050∿0.132,while those between the Korea and nine other populations excluding the Tsushima were 0.137∿0.201. The genetic distances between H. hallowelli from Amami and the 11 populations of H. japonica were 0.974∿1.131,while those between H. chinensis from Taiwan and the 11 populations of H. japonica were 1.177∿1.360. The genetic distance between H. hallowelli and H. chinensis was 0.596. The phylogenetic relationship of the 13 populations of the three Hyla species was examined by drawing a dendrogram by the UPGMA method. It was found that H. japonica was first divided from the others which later became H. hallowelli and H. chinensis. From H. japonica, the Korea population first diverged, and then the remaining populations were roughly divided into three groups.