Fecal pellets from 115 federally endangered West Virginia northern flying squirrels (Glaucomys sabrinus fuscus) were collected in the Monongahela National Forest, West Virginia during the spring and fall in 1989–1991 and analyzed to determine the squirrel's diet. In spring the squirrel's diet consisted primarily of tree buds, lichens and hypogeous fungi. In fall hypogeous and epigeous fungi and beechnuts were the most common food items. The epigeous fungi were in the families Boletaceae, Strophariaceae and Russulaceae. Hypogeous fungi in the genus Elaphomyces were consumed by 50.8% of the squirrels in the spring and 48.2% in the fall. Five other hypogeous taxa were identified in 5.2% of the samples. All hypogeous species identified in the scats form mycorrhizal relationships with forest trees and are dependent on mycophagy for spore dispersal. West Virginia northern flying squirrels facilitate spore dispersal of these mycorrhizal fungi and may contribute to the health of tree species in high elevation red spruce (Picea rubens)/northern hardwood forests in West Virginia.