Phylogeographic analyses of arctic organisms provide spatial and temporal frameworks for interpreting the role of climate change on biotic diversity in high-latitude ecosystems. Phylogenetic analyses based on 673 base pairs of the mitochondrial control region from 95 arctic hares (Lepus arcticus, L. othus, L. timidus) and 2 other Lepus species identified 6 strongly or moderately supported clades. The 3 arctic hare species are closely related, but phylogenetic discontinuities were found at the eastern and western boundaries of Beringia, the latter not previously identified as a species boundary. The locations of these discontinuities are congruent with previously described genetic breaks in Arctic plants, birds, and small mammals. Similarly, the finding of a Beringian clade corroborates previous studies identifying Beringia as a refugium. A coalescent view of a population on Seward Peninsula, Alaska (eastern Beringia), did not, however, provide a genetic signature of population expansion. In contrast, a Greenland population did show a signal of expansion.