In two small adjacent groups-kumandinias and chelkanians-the distribution of G1m(a), G1m(x), G1m(f), G3m(b1), G3m(b5) and Km(1) serum allotypic markers was studied. Gmf;b haplotype frequency in kumandinians was found to be 0.310; in chelkanians living eastward it was 0.212. Gma and Gmax frequencies were observed to be 0.606 and 0.084 in the former and 0.687 and 0.101 in the latter. Km1 frequency was found to be 0.074 in kumandinians and 0.087 in chelkanians. Unusual Gm(a, f) henotype was observed in both groups with a frequency lesser than 5%.