Medial arterial calcification is frequently seen in diabetic patients with severe diabetic neuropathy. Sixty patients (19 diabetic and 41 non-diabetic) were examined radiologically for typical Mönckeberg's sclerosis of feet arteries 6-8 years after uni- or bilateral lumbar sympathectomy. Fifty-five out of 60 patients (92%) revealed medial calcification. This calcification was observed in both feet of 93% of patients, who had undergone bilateral operation. After unilateral sympathectomy the incidence of calcified arteries on the side of operation was significantly higher than that on the contralateral side (88% versus 18%, p less than 0.01). Although diabetic patients showed longer stretches of calcification than non-diabetic subjects, the difference was not significant in terms of incidence and length. Of 20 patients who had no evidence of calcinosis pre-operatively, 11 developed medial calcification after unilateral operation exclusively on the side of sympathectomy. In seven patients calcinosis was detected in both feet after bilateral operation. In conclusion, sympathetic denervation is one of the causes of Mönckeberg's sclerosis regardless of diabetes mellitus.