Although the impairment of autonomic function has been described in alcoholic subjects, there is no evidence for such a dysfunction to be due to damage of autonomic centers or peripheral small caliber fibers. To investigate the function of peripheral fibres of the autonomic nervous system, we have carried out an electrophysiological study of the sympathetic skin response (SSR) in the hands and feet in 70 alcoholic and in 33 non-alcoholic subjects. In the hand, SSR recordings were done simultaneously in the palm and finger tip by stimulating the median nerve at the wrist. A conventional electrophysiological study performed in the same patients was used to classify them according to the presence or absence of electrophysiological criteria for peripheral polyneuropathy (ECPN). In analyzing the results of the SSR test, we found absent responses in the finger tip with present responses in the palm in 18 patients, 13 of them with ECPN. Absent responses in the feet were observed in 37 patients, 28 of them with ECPN. From our findings, it is concluded that alcoholics suffer from a dysfunction of sympathetic sudomotor activity due to axonal involvement of the most distal segments of the nerves.