Wing and tail injuries and defects appeared commonly among members of pallid bat (Antrozous pallidus) colonies in southern Arizona. These injuries and defects can be grouped into the following categories: membrane holes, bone abnormalities (nonsymmetrical forearm, curved forearm and fingers, protruding bones, broken fingers, and broken tails), missing membrane parts, and embedded thorns and cactus spines. Some of these injuries and defects may be due to certain inherent problems occurring in conjunction with bat-type flight surfaces. The success of bats in spite of such disadvantages is perhaps due to: "extra" wing-load capacity, the ability to fuse broken or dislocated bones, the ability to heal rips and fill in membrane holes, a tolerance of asymmetry, and an ability to limit the continual danger of infection following membrane injury.