Normally, the wings are assumed to be symmetrical, since radical departure from symmetry is known to hinder flight. The objective of the present paper was to investigate the symmetry of the wing structure in a population of common vampire bats, Desmodus rotundus. The bones of both wings were measured, and the area of each wing was calculated. Asymmetry was found, with males having a larger number of asymmetric bone structures than females. Moreover, both directional asymmetry and antisymmetry were identified for the males, whereas for the females only fluctuating asymmetry was found. However, although asymmetry does occur, it is generally compensated for by complementary changes in the structures of the other wing. We believe that by keeping the wing area symmetrical, potential aerodynamic problems may be minimized.