Mountain hares (Lepus timidus hibernicus Bell) are extremely vagile and commute up to 3 km daily within their home ranges. However, observational and mark–recapture evidence suggests that they do not disperse far in their lifetime. Whether behavioral factors such as philopatry are promoting genetic structuring in this largely solitary species is not known. We examined genetic structure in the mountain hare using microsatellite markers from 321 mountain hares from across southern Ireland. Genetic differentiation ranged from low to moderate (pairwise F_ST = 0–0.116), and across distances of 200 km, F_ST was not correlated with geographic distance, suggesting possible population fragmentation. Home ranges of males in this species are significantly larger than those of females during the breeding season, suggesting that dispersal may be male-biased. Mean corrected assignment index (mAI_C) was lower in males (−0.280) than in females (0.403). F_ST was lower among male cohorts of population samples (0.040) than among female cohorts (0.051), but the difference was not significant. These results are consistent with natal dispersal of nonresident males into the sampling areas.