Forty-five patients suffering from intermittent claudication were admitted to a double-blind non-crossover study. Three groups were constituted at random and treated for 2 months with either 100 mg suloctidil t.i.d. or 1.5 mg dihydroergotoxine methylate t.i.d. or placebo. From the results of measurements of pain-free walking distance and venous occlusion plethysmography recordings, suloctidil was shown to be active and significantly superior to dehydroergotoxine and placebo: in the two latter groups a decrease in calf blood perfusion after 2 months was also noted. The physician's overall assessment of response to treatment showed that suloctidil and dihydroergotoxine were significantly superior to placebo, and that suloctidil was significantly better than dihydroergotoxine.