Nerve palsy is an uncommon but acknowledged complication of total hip replacement. The overall prevalence is approximately 1%. The sciatic nerve, or the peroneal division of the sciatic nerve, is involved in nearly 80% of cases. The risk of nerve palsy in association with total hip replacement is increased for female compared with male patients, with a diagnosis of developmental dysplasia, and with patients undergoing revision surgery. In the majority of cases, the origin of the palsy is unknown. Because peripheral nerves are sensitive to compression, unrecognized compression may play a role in these cases. The prognosis for neurologic recovery is related to the degree of nerve damage. Complete, or essentially complete, recovery occurs in approximately 41% and another 44% have only a mild deficit. Approximately 15% have a poor outcome characterized by weakness that limits ambulation and/or persistent dysesthesia. Patients with some motor function immediately after the operation and those who recover some motor function within approximately 2 weeks of surgery have a good prognosis for recovery. In general, recovery of femoral nerve palsies is more predictable than that of sciatic palsies.