Home ranges of mountain hares Lepus timidus were studied in boreal forests in Finland and compared to those on the British Isles and in Sweden. During 1998–2001 we radio-tracked 22 hares. Mean yearly home range size was 206 ha. Home ranges were largest in late winter-spring (mean: 202 ha) and smallest in autumn (mean: 71 ha). Home ranges were rather stationary, and only minor shifts in home range locations occurred between seasons. The hares used, however, partly different core areas in different seasons. Home ranges were much larger in the boreal forests of Finland, where the climate is cold, than in the moorlands and grasslands of the British Isles, where the climate is much milder. Home ranges in Finland were similar in size to those in the boreal forests of Sweden. In Finland and Sweden, winters are harsh, the growing season for plants short and the field layer vegetation is covered by snow from November until late April. The large home ranges in the boreal forests are probably mainly due to the low food availability in this environment.