BACKGROUND: Beraprost sodium (BPS) is a new stable, orally active prostaglandin I2 analogue with antiplatelet and vasodilating properties. We performed an prospective, multicenter, open clinical trial to assess the efficacy and safety of BPS in type 2 diabetic patients complicated with arteriosclerosis obliterans (ASO). METHOD: We recruited 34 type 2 diabetic patients complicated with ASO at 5 different university hospitals. Patients received BPS 40 g tid for 6-week. Patients performed a subjective and objective assessment of treatment usefulness at 2- and 6-week. Safety was assessed by obtaining clinical data and history. RESULTS: There was a significant difference between before and after treatment for changes regarding the items "chillness", "numbness" and "rest pain". An improve ment in intermittent claudication distance at the 2-or 4-week interval was achieved. Ankle Pressure Index (API) was not statistically different. The side effects including fever, myalgia, indigestion were subtle and the patients' compliance is good. CONCLUSION: These results show that BSP is an effective and safe symptomatic treatment of Type 2 diabetic patients with ASO.