Motor neuropathy of a lower extremity is well recognized potential complication of procedures performed on patients in a lithotomy position. Mechanisms of nerve injury are unclear but the incidence of perioperative nerve injuries can be reduced if anesthetists are aware of their causes and pathophysiolgies. It is important to note that reduced duration in lithotomy position may reduce the risk of lower extremity neuropathies. We experienced two case of common peroneal nerve palsy after lithotomy positioning. Diagnosis was based on history, a clinical examination and electrophysiologic studies. A neurologic examination revealed hypersthesia over the dorsum of the left foot with inability to perform active dorsiflexion. Electrophysiologic studies showed delayed latency and low amplitude of nerve action potential.