Our 20-year results with in situ saphenous vein grafting in the lower extremity were reviewed and compared wih those where reversed saphenous veins were employed. The ten-year patency rates for both types of grafts terminating at the popliteal artery ranged from 41% to 43% and showed no statistical difference. The reversed saphenous vein performed well in the femoropopliteal position because the vein is usually of the same size at the knee as in the groin and thus does not taper when reversed. We have identified from our study specific indications for the in situ operation. These indications are the presence of small or substantially tapering or bifurcating great saphenous veins that otherwise would be unsatisfactory for conventional reversed vein grafting. We believe that the in situ saphenous vein operation should be considered before resorting to prosthetic leg grafts that carry a lower long-term patency, particularly when carried below the knee.