As part of a study stimulated by the decline in numbers of the barren-ground caribou in Northern Canada, the quality of their winter forage plants was studied. Twenty-five lichens and eight vascular plants, comprising the important forage species on the winter range of the animals, were collected in June, September, and March. They were analyzed for crude protein, ether extract, crude fiber, ash, calcium, and phosphorus.In general, lichens were found to be low in protein, calcium, and phosphorus in relation to the estimated nutrient requirements of the caribou. They do however appear to supply a major part of the energy needs of this species. An attempt has been made to list the groups of lichen species studied in the order of animal preference. Seasonal fluctuations in chemical composition are indicated.