Genetic structure of four Kamchatka subpopulations (675 individuals) was estimated for 25 erytrocyte and serum systems, some blood groups and for taste sensitivity to PTC. 23 of 38 loci examined are completely monomorphic. These are: AK, Ca-1, Cat, Dia, Est1-4, GOT, G-6-PD, LDH A and B, MDH, PGM2, SoD, Hb alpha and beta, ChE1, Lap, Alb, Cp, Tf, Rh. Following allele frequencies were found for polymorphic loci: AcPA = = 0.616; AcPB = 0.383; AcPC = 0.0015; EsD1 = 0.882; GLO - I1 = 0.156; GPT1 = 0.611; PGDA = = 0.959; PGM1(1) = 0.953; ChE2+ = 0.039; Gc1 = 0.888; Hp1 = 0.173; r(0) = 0.620; P(A) = 0.201; q(B) = 0.179; le = 0.192; M = 0.397; P1+ = 0.585; t = 0.371. According to monomorphic and polymorphic loci set, Kamchatka Koryaks are rather similar to other ethnic North-East Asiatic groups, being the most approximate to Reindeer Chuckchies and the most remote from Alaskan and Asiatic Eskimos. In other words, the extent of genetic differences between Kamchatka Koryaks and North-East populations corresponds to the geographic distribution and the degree of ecological differences in these populations. Analysis of interpopulation heterogeneity permitted to reveal the extent of contribution of individual loci to "differentiation" of North-East ethnic groups. The possible influence of ecological factors on interpopulation and intersubpopulation heterogeneity of the loci analysed is discussed.