15 patients with arteriosclerotic lesions in the extracranial brain arteries, randomly selected, were treated with an infusion of 250 ml physiological NaCl and 25 ml Ginkgo biloba extract (Tebonin). A second group (n = 15) received 250 ml NaCl without drugs stimulating blood flow. The skin microcirculation was measured in vivo by means of a helium-neon laser at one of the 4 extremities. Perfusion increased significantly (p less than or equal to 0.01) in response to Ginkgo biloba extract als composed with the response in the control group. The results justify the administration of Ginkgo biloba extract in vascular diseases.