Neuropathies are infrequent but potentially debilitating complications in surgical patients. Although the most common of these affect the peripheral ulnar and sciatic nerves, more centrally located sets of nerves such as the brachial plexus and lumbosacral nerve roots also can be affected perioperatively. Traditionally, these neuropathies have been considered avoidable and associated with inappropriate patient positioning intraoperatively. Recent epidemiologic and anatomic studies suggest, however, that various factors other than intraoperative positioning may contribute to the development of neuropathies. For example, it is now clear that a large proportion of surgical patients who subsequently have development of ulnar neuropathies are asymptomatic during the first several postoperative days. Further delineation of the epidemiology and causes of the various perioperative neuropathies should lead to innovative interventions and clinical trials of their effectiveness to decrease the frequency and severity of these complications in surgical patients.