To test the association between body size and degree of folivory and to examine the different food habits in sympatric arboreal herbivorous mammals, we investigated diets of 2 flying squirrel species (Petaurista petaurista and Eoglaucomys fimbriatus) sympatrically distributed in the Himalayan moist temperate forest of northern Pakistan. P. petaurista and E. fimbriatus used 27 and 28 tree species, respectively. Both flying squirrel species used the same 27 tree species. However, frequency of tree species used by P. petaurista was significantly different from that used by E. fimbriatus. P. petaurista was significantly more folivorous than was E. fimbriatus. Preference of P. petaurista for leaves may be an important factor preventing competition for resources between these species. We conclude that larger body size in flying squirrels is associated with the tendency toward a foliage diet.