Of various factors which might limit barren-ground caribou (Rangifer tarandus groenlandicus) populations, destruction of range by fire is one. Fire, caused by lightning or man, generally affects only the caribou's winter range in the taiga or northern regions of the boreal forest. On the summer range in northern Canada, fires are rare and usually limited in extent because of the heterogeneous mixture of wet and dry tundra and barren areas of rock or sand. The Canadian Wildlife Service's intensive caribou research program included an evaluation of the effects of fire on four key upland wintering areas within the taiga. Some primary objectives were (1) to determine the portion of burned winter range and whether it has increased in recent years; (2) to determine the effects of fire on the usable standing crops of terrestrial forage and arboreal lichens; and (3) to determine the effects of fire on range use by the barren-ground caribou and moose (Alces alces).