This study examines the hypothesis that postoperative ankle-brachial pressure index (postop ABI) can be accurately predicted using noninvasive preoperative segmental leg pressure measurements. Seventy-three patients who underwent successful reverse autogenous vein femoropopliteal bypass and who had pre- and postoperative segmental leg pressure measurements were examined. Predicted postop ABI was estimated using the following formula: Postop ABI = 1 + (Preop ABI) - (Preop BKI). (BKI = below-knee brachial pressure index). Using this formula, 56 out of 73 (81%) patients had a measured postop ABI +/- 20% of predicted postop ABI. Five out of 73 (7%) patients had postop ABI less than 80% predicted, while 12 out of 73 (16%) patients had postop ABI greater than 120% of predicted. All patients with postop ABI greater than 120% of predicted had apparent tibial artery occlusive disease as indicated by preoperative gradients (BKI-ABI) greater than 0.15.