This study determined the outcome of the contralateral internal iliac artery (IIA) in patients undergoing aortouni-iliac (AUI) endovascular abdominal aortic aneurysm repair (EVAR) with a femorofemoral bypass.This retrospective study evaluated 131 consecutive patients undergoing AUI EVAR with femorofemoral bypass at the McGill University Health Center from October 2001 to November 2010. One hundred patients with preoperatively patent contralateral IIA met inclusion criteria for the study. Preoperative demographics and preoperative and postoperative contrast-enhanced computed tomography (CT) scans with multiplanar reconstruction were reviewed for all patients. The last available postoperative CT imaging for all patients was identified and evaluated for contralateral IIA patency. Patency in preoperative and postoperative CT scans was defined as contrast enhancement of the IIA in continuity with the external iliac artery and absence of >50% stenosis at the origin of the IIA. Clinical outcome focused on postoperative pelvic ischemia and reported symptoms of buttock claudication.Mean age at the time of operation was 77.6 ± 6.7 years, and 78% were male. Mean clinical follow-up was 29.2 months after surgery, and mean follow-up of imaging with intravenous contrast was 30.6 months. The last imaging follow-up showed 67 patients (67%) had a patent contralateral IIA and that the IIAs in 33 patients (33%) were occluded (25 [76%]) or stenotic (8 [24%]). Of the patients with IIA occlusion, 80% (20 of 25) were occluded on the first postoperative imaging (median, 8.5 days). Buttock claudication was reported in 18% (6 of 33 patients) with an occluded IIA compared with only 3% (2 of 67 patients) of patients with a patent contralateral IIA on final imaging follow-up (18% vs 3%; P = .014). There were no observed cases of buttock necrosis, spinal ischemia, or colonic ischemia.Our findings suggest that AUI EVAR with femorofemoral bypass is associated with a significant incidence of contralateral IIA malperfusion on postoperative CT imaging. Occlusion appears to occur early in the postoperative period in most patients, and patient-reported buttock claudication is observed significantly more frequently in patients with an occluded IIA compared with those with a patent IIA. More serious pelvic ischemic complications were not seen in this series. Further study is required to determine whether modification of the procedure can prevent contralateral IIA occlusion and the development of buttock claudication.