Anthropogenic impacts such as habitat conversion and fragmentation, in combination with predator control and fur trapping, are responsible for substantial reductions in the ranges of many carnivores worldwide. The wolverine (Gulo gulo) is classified as vulnerable throughout the Holarctic Region by the International Union for Conservation of Nature and Natural Resources, is designated as endangered in eastern Canada, and has been petitioned twice for listing with the United States Fish and Wildlife Service. We examined genetic structure across populations in northwestern North America by using mtDNA sequences of the left domain of control region and the complete cytochrome-b gene (Cytb). Nucleotide diversity (π) and sequence divergence among haplotypes were low for both markers, whereas haplotype diversity (h) was generally high. Genetic divergence (F_st) values were significant, and high for control region (0.21), and moderate to high for Cytb (0.16). Globally, Eurasian and Scandinavian wolverines were distinguishable from North American. Within North America, the Kenai Peninsula, southeastern Alaska, and Nunavut populations were distinctive. Comparisons with studies based on nuclear markers reveal greater geographic structure in these maternally inherited mitochondrial markers, a finding consistent with male-biased dispersal in wolverines. Conservation plans for these medium-sized carnivores should emphasize maintenance of genetic diversity and recognize that successful dispersal of females between populations may be limited.