Arterial bypass for the chronic ischemia of the lower extremities underlying atherosclerotic obliterans has been performed with a number of alternative conduits from 1941 by Kunlin. It is indicated for the limb salvage of patients with threatened limb loss despite of several controversies in surgical treatment of atherosclerotic obliterans. From March 1991 to January 1995, 26 arterial bypasses were performed in 23 patients with the chronic ischemia of the lower extremities in our hospital. Their mean follow up period is 18.9 months ranging from 4 months to 44 months. Mean age is 60.9 years ranging 47 years to 76 years and the most prevalent incidence is the 6th decade. 21 patients are male and 2 patients are female. 19 of 23 patients are smokers. Clinical classifications by Fontaine are class II[21.7% , class III[34.8% and class IV[43.5% .Diabetes mellitus[47.8% , hypertension[43.5% , hyperlipid-emia[26% , tuberculosis[21.7% , cerebrovascular accident[13.0% and cardiac diseases[8.7% are associated. Aorto-single femoral bypass in 4 cases, aorto-bifemoral bypass in 5 cases, aortofemoral & femoropopliteal bypass in 2 cases, femoropopliteal bypass in 10 cases, popliteotibial bypass in 3 cases, femoropedal bypass[composite graft bypass in 2 cases were surgically approached. There are complicated early thrombosis in 4 cases those are required immediately reoperation, wound infection in 3 cases, hematoma in 3 cases, and so on. Postoperative complication rate is 53.8%.Postoperative patency rates are 84.6% at 6 months, 75.0% at 1 year, 70.0% at 2 years and 66.7% at 3 years. We usually used 6 mm & 8 mm graft for bypass, and the rate of thrombosis formation is 28.6%[2/7 in 6 mm graft and 12.5%[2/16 in 8 mm separately. In according to the graft materials, the rate of thrombosis formation is higher in the group using artificial graft than in that using autologous saphenous vein[16.6% vs 12.5% . Limb salvage rate is 76.9%. Postoperative mortality rate is zero %.