The main object of treatment in chronic occlusive arterial disease is to increase blood flow for ischemic limb. In case of severe symptoms and signs such as rest pain, ischemic ulcer and gangrene with poor angiographic distal run-off, conservative medical treatment is recommended. Beraprost sodium(TRK-100) is the oral preparation of a prostaglandin I2,that has known to increase blood flow, prevent secondary thrombi formation, suppress platelet aggregation,increase oxygen perfusion pressure, increase deformability of erythrocyte, and protect endothelial cell from ischemia and inflammation. From September 1995 to January 1997, 23 patients among 42 patients with severe ischemic ulcer and poor angiographic distal run-off underwent Beraprost oral treatment in the Department of Surgery, Ulsan-chungang and Yeungnam University Hospital: Buerger's disease(TAO) in 14 and arteriosclerosis obliterans(ASO) in 9 cases. Daily dose was 120microgram(6 tablets #3) and medicated for consecutive 6 weeks. To detect the changes of symptoms, signs & ischemic ulcer size and occurrence of side reactions, inquiries, photography and laboratory tests were checked at prior to medication and 2, 4 & 6 weeks after medication. The results were as follows. There were 21 men and 2 women, ranging in age from 23 to 77 years old with mean of 44 years old and in body weight from 43 to 75kg with mean of 61kg. Forteen cases(60.9%) were improved but 2 cases(6.2%) were aggravated on rest pain and coldness. Improval rate on ischemic ulcer & granulation size was 70%(16 cases) and 82.6%(19 cases) respectively. There noted infection in 7 cases(30.4%). Overall improval rates were 70.0%(16 cases), general safety rates were 95.7%(22 cases), and usefulness of the drug was shown in 16 cases(70.0%). One case(3.2%) of indigestion was reported as side reaction. There noted no significant hematologic, urinary or biochemical abnormalities. In conclusion, Beraprost treatment for severe ischemic limb had a beneficial effect on relieving pain and ulcer healing and proved safety in its use.