A retrospective review of 298 saphenous vein femoropopliteal bypasses performed for femoral artery occlusive disease over a 13-yr period was carried out. The purpose of the study was to assess factors which influence long-term graft patency. Follow-up was 95.3% complete. Results were analyzed with the aid of IBM data processing equipment and standard statistical methods. The cumulative patency rate for patients with good arteriographic runoff, regardless of ischemic symptoms, was 81% at 5 yr. This value was 20% superior to that of patients with fair-poor outflow vessels, (P < 0.05). There was no statistical difference in patency rates in grafts performed for mild ischemic symptoms and those having limb salvage procedures under similar conditions of runoff. The age of the patient at the time of femoropopliteal grafting influenced long-term patency. With the exception of a small group of patients over 80 yr, there was a progressive improvement in cumulative patency rate with each successively older decade. Patients operated on in the 8th decade had cumulative patency rates 10% greater than those of their counterparts in the 5th decade. Of 150 patients with fair-poor runoff, the cumulative patency rate of 112 with lumbar sympathectomy was compared with 38 not having had the secondary procedure. Those without sympathectomy suffered 12% more graft occlusions during the 1st 12 mo. than did patients having had either a previous or concomitant sympathectomy (P < 0.05). The temporary increase in femoral artery blood flow produced by lumbar sympathectomy may, in some situations, help to maintain graft patency during the 1st few critical mo. when the highest percentage of graft failures occur. There was no discernible effect of sympathectomy on long-term graft patency.