Because of anthropogenic factors in the early 1900s that caused populations to decline dramatically, wolverines (Gulo gulo) currently are designated as endangered in eastern Canada and classified as vulnerable throughout the Holarctic Region by the International Union for Conservation of Nature and Natural Resources. Although numerous examples exist that illustrate the utility of genetic data for development of conservation plans, no study has investigated the genetic structure of natural populations of wolverines. We assessed allozymic and mitochondrial DNA (mtDNA) variability of wolverines within and among 5 sites from the Northwest Territories, Canada. Five of 46 presumptive allozyme loci were polymorphic. Estimates of heterozygosity (2.6%) and polymorphism (11.6%) were lower than values reported for most mammals but were within the range reported for Carnivora. To evaluate levels of variation in mtDNA, we sequenced the left domain of the control region. Six variable nucleotide sites were observed, resulting in 9 haplotypes of mtDNA. Within-site diversity of haplotypes (h) was high, but within-site diversity of nucleotides (π) was low, indicating little sequence divergence among the 9 haplotypes. Sequence data for mtDNA revealed considerably more genetic partitioning among sites (ϕ_ST = 0.536) than did allozyme data (F_ST = 0.076). Based on fixation indices, gene flow estimates (Nm) were moderate for nuclear markers but low for mtDNA loci. These findings suggest that, although wolverines maintain large home ranges, they exhibit fidelity to discrete areas, gene flow is predominantly male-mediated, and most sites in the Northwest Territories are genetically independent and thus represent populations. Therefore, any conservation plan for wolverines in the Northwest Territories must consider preservation of populations if genetic diversity of this taxon is to be maintained.