We investigated involvement of the peripheral nervous system in 6 patients with amyotrophic chorea-acanthocytosis. Electromyographic and neurographic findings, and pathological changes as demonstrated by examination of biopsy specimens of muscle and sural nerve indicate that most patients had an axonal sensorimotor polyneuropathy with more pronounced involvement of the distal portion of the nerves. Results obtained in one patient raised the question of an anterior horn cell disorder.