The gene pool structure was studied for the indigenous population of the Sakha Republic (Yakutia). The composition and frequencies of Y-chromosome haplotypes in Yakuts were characterized. Six haplogroups were observed: C3×M77, C3c, N*, N2, N3a, and R1a1, N3a being the most common (89%). The gene diversity computed from the haplogroup frequencies was low in all samples examined. Gene differentiation was analyzed by AMOVA with two marker systems (haplogroup frequencies and Y-chromosomal microsatellite haplotypes) and was estimated at 0.24 and 2.85%, respectively. The frequencies and molecular phylogeny of the YSTR haplotypes were studied for the N3a haplogroup. In total, 40 haplotypes were found in Yakuts. Evenks and Yakuts displayed highly specific overlapping N3a haplotype spectra, atypical for other Siberian ethnic groups. Cluster analysis with N3a YSTR haplotypes showed that Yakuts are isolated from other Turkic-speaking populations of Southern Siberia. The genetic diversity generation time was estimated at 4450 ± 1960 years for the Yakut haplotype spectrum. In contrast to mtDNA data, the results suggest a significant contribution of the local Paleolithic component to the Y-chromosome gene pool of Yakuts. Ethnogenetic reconstructions were inferred from the diversity and phylogeography of the N3a haplogroup in Siberia.