OBJECTIVE To determine the incidence of entrapment neuropathy in patients with amyotrophic lateral sclerosis (ALS). Although it is well known that patients with motor neuron disease may have coexisting focal neuropathies, their prevalence has not been previously determined. METHODS Electrophysiologic studies (EMG/NCS) were reviewed from 126 patients with ALS seen at a university-affiliated hospital from 1991 to 1994. Every patient had an EMG/ NCS consistent with motor neuron disease (i.e., active and chronic denervation in at least 3 body regions). RESULTS Forty-three percent (54 patients) had evidence of a neuropathy. Abnormalities included median neuropathy at the wrist in 15 (12%), ulnar neuropathy at the elbow in 18 (14%), nonlocalized ulnar neuropathy in 10 (8%), and peroneal neuropathy at the fibular head in 2 (2%). Furthermore, 9 patients (7%) had a superimposed polyneuropathy. Of these 54 patients, 7 (13%) had clinical symptoms of their neuropathy. CONCLUSIONS Coexistent focal or generalized neuropathies in ALS are not uncommon. Careful attention to these abnormalities may decrease morbidity in these patients.