To determine predictors of long-term patency in extra-anatomic bypass grafting, the authors studied retrospectively the charts of 134 patients who underwent bypass grafting (axillofemoral in 17, axillobifemoral in 32 and femorofemoral in 85). Of the study group, 64% were men; the mean age was 65 +/- 12 years (+/- SEM). The indications for grafting were limb salvage (102), claudication (27) and replacement of septic grafts (5), and for using the extra-anatomic route included high risk (83), sepsis (8) and unilateral disease (34). Operative mortality was 6% and the early graft occlusion rate 7.4%. The late death rate was 44%. At 3 years, the life-table patency rates for the various procedures were axillofemoral 52.5%, axillobifemoral 67.7% and crossfemoral 86.9%. Smoking significantly (p less than 0.05) decreased the patency rate, but diabetes did not. However, amputation was more frequent in diabetics. Indications for operation did not alter patency rates, but did affect operative mortality. The authors conclude that extra-anatomic bypass grafting is highly successful, but not as successful as anatomic bypass. When appropriate, the axillobifemoral graft is preferred to the axillounifemoral graft because of its increased patency. Crossfemoral grafts must be carefully monitored to ensure that no donor limb stenosis occurs and this procedure should not be attempted unless the disease is truly unilateral.