Restriction polymorphism of mitochondrial DNA (mtDNA) isolated from the blood of 107 Koryaks, 28 Northern Altaians, and 23 Kets was studied. The results were compared with similar data that in aggregate characterized haplotypes of 569 individual DNAs from 13 Siberian populations, in order to elucidate the genetic similarity and differences between mtDNA haplogroups of native Siberians and Americans. Natives of Siberia are distinguished by the significant variation of the composition and frequency of three (A, C, and D) of four haplogroups characteristic of American Indians. In the full composition, all four haplogroups-A, B, C, and D-are found only in a sample of Northern Altaians. The peculiarities of their geographical distribution in Asia allow us to consider the southern regions of Siberia and the adjacent territories of Central and East Asia as the site inhabited by the ancestors of the first wave of migrants to North America.