OBJECTIVE Femorofemoral bypass (FFB) is used in selected patients when aortobifemoral bypass (AFB) is believed to be inappropriate because of high operative risk or predominantly unilateral iliac artery occlusive disease. We examined concurrent patients who underwent either FFB or AFB to better understand the appropriate use of FFB. METHODS The characteristics and outcomes of patients who underwent FFB and AFB during 1986 to 1991 at our institution were retrospectively reviewed. Primary measures of outcome included patient survival, graft patency, limb salvage, and hemodynamic performance of FFB and AFB. Further analysis was performed after substratification for low versus high risk and claudication versus limb threat as the indication for surgery. RESULTS FFB was performed in older patients with more medical comorbidities when compared with AFB. Long-term graft patency was inferior after FFB compared with AFB (60% vs 85% at 3 years, p < 0.01). However, both FFB and AFB achieved limb salvage in more than 85% of patients at 3 years. When patients at low risk undergoing nonemergency AFB were compared with patients at low risk who underwent FFB and who had no contraindication to AFB, FFB proved inferior to AFB as measured by graft patency (primary patency 61% vs 87% at 3 years, p < 0.03) and hemodynamic performance (predicted ankle-brachial index with perfect outflow 0.82 after FFB vs 1.03 after AFB). On the basis of a detailed analysis of patient and graft risk factors, we could not explain the inferior patency rate of FFB, although our analysis suggested that inadequate inflow may contribute. CONCLUSIONS FFB is inferior to AFB as measured by patency and hemodynamic function. This inferior performance is independent of indications for FFB. AFB should remain the standard therapy for patients at low risk with iliac occlusive disease, but FFB provides adequate function and limb salvage in patients at high risk.