175 by-pass operations were performed for femoro-popliteal atherosclerosis during the period January 1967-April 1975. 154 were femoro-popliteal vein by-pass grafts. The material in addition includes 12 distal tibial arterial by-pass grafts, 6 homologous vein grafts, 2 Sparks prosthesis and 1 dacron graft. In the femoro-popliteal vein by-pass group 51% were operated for rest-pain or distal gangrene, while 49% had intermittent claudication. The 4 year patency rate in the two groups was 54% and 66% resepctively and was more favourable when the distal anastomosis was placed above than below the knee. However, the latter group had more severe ischaemic symptoms and the difference is probably in part due to case selection. The results were also more favourable when the proximal anastomosis was placed on the common femoral artery. The operative mortality was 38%. Vein by-pass to the lower leg arteries had a 2 year patency of only 34%. Semi-closed endarterectomy is preferred to homologous vein, Sparks prosthesis or dacron grafts where no sufficient vein for grafting exists. It is concluded that saphenous vein by-pass is the method of choice in patients where femoro-popliteal reconstruction is indicated.