Restriction polymorphism of the mtDNA cytochrome b gene was studied in nine sable Martes zibellina L. populations from three introduction foci of Khabarovsk and Kamchatka sables in Magadan oblast: Olya, Kolyma, and Omolon. For comparison, similar studies were performed with the populations of central Kamchatka and Khabarovsk krai. In total, 444 DNA specimens were examined. Three mtDNA haplotypes (A, B, and C) proved to occur at various frequencies in the populations under study. The sable population system displayed high differentiation (FST = 22.3%). The populations of the Olya focus were most similar genetically to the populations of Kamchatka; those of the Omolon focus were similar to the Khabarovsk populations, and those of the Kolyma focus occupied an intermediate place. The observed spatial heterogeneity of the sable populations of Magadan oblast was explained in terms of the formation of the introduction foci of Kamchatka and Khabarovsk sables, starting from the 1950s.