Data on the first examination of the CYP1A1 and CYP2D6 genes' polymorphism in the populations of Tundra Nentsis (Yamalo-Nenetskii Autonomous District) and migrant population of Western Siberia (Novosibirsk oblast and Altaiskii krai) are presented. The frequency of the 2D6*4 mutant allele in Tundra Nentsis, characterized by a two-component Caucasoid and Mongoloid origin, was shown to be intermediate in Caucasoid and Mongoloid populations. The frequencies of the 2D6*4 and 1A1Val* mutant alleles across migrant inhabitants of Western Siberia (Caucasoid populations) were similar to that reported for the Caucasoid populations overall. Distribution of the CYP1A1 genotypes (Ile/Ile, Ile/Val*, and Val*/Val*) in Tundra Nentsis was similar to that found in Mongoloid groups. However, the frequency of the 1A1Val* allele in Tundra Nentsis was 1.5 times higher than that in the Southern Mongoloid populations (Chinese, Koreans, and Japanese).