Chi-square contingency table analysis of phenotypic (genotypic) and gene frequencies of erythrocyte and blood serum groups and enzymes in a group of reindeer hunter and fishermen revealed heterogeneity within the population studied. Four out of twelve loci which have been compared were found to be involved in the process of differentiation into two local subgroups (subpopulations). No statistical differences have been observed between samples arbitrarily representing three generations. The data obtained support the hypothesis that the whole population still preserves the state of the stability. Traditional migration from adjacent populations close to nganasans by language and culture has made an important contribution into heterogeneity found in nganasans.