The incidence, type arid distribution of polyneuropathy in patients with chronic obstructive pulmonary disease (COPD) were assessed and also analyzed the causative factors. Forty-four patients, mean age 66.1 years (42 male, 2 female), have been investigated with arterial gas analysis, pulmonary function test, clinical and electrodiagnostic studies. None of them had conditions known to affect the peripheral nervous system such as metabolic disorders or drugs. In a selected group of 44 patients, electrophysiological findings of polyneuropathy were found in 22 patients(50%), clinical polyneurtpathy were diagnosed in 13 patients(9 patients were diagnosed by electrophysiological studies, 4 patients were normal by electrophysiological studies). These findings indicate that subclinical polyneuropathy( 13 patisnts, 30%) more conimorily occurs than clinical polyneuropathy( 9 patients, 20%) in associated with COPD. In the patients with polyneuropathy, the lesions were predominant axonal degeneration, the changes were more involved in leg than arm, more frequently affected sensory fibers. We could not find etiologic factor to cause polyneuropathy in COPD patients.