Endograft limb extension to the external iliac artery with embolization of an internal iliac artery (IIA) may be necessary in patients with abdominal aortic aneurysms (AAAs) extending to the common iliac artery to prevent endoleak during endovascular aortic aneurysm repair (EVAR). Coil embolization of the IIA can be performed at the same operative setting as EVAR or, alternatively, as a staged procedure. Most interventionalists favor the latter approach to avoid excessive contrast material and prolonged operative time. We investigated the clinical outcome of concomitant vs staged unilateral IIA embolization in the setting of EVAR. Vascular surgeons at our institution treated 24 patients with infrarenal EVAR and unilateral coil embolization of the IIA from October 1, 2000 to June 30, 2005. All patients had normal renal function. The details of the operative procedure and perioperative complications were compared in patients undergoing concomitant vs staged procedures. Follow up was 1 to 40 months (average, 11 months). Among the 24, 16 underwent concomitant unilateral IIA embolization in the setting of EVAR and eight patients underwent the staged procedure. Average duration of operative time (298 vs 284 minutes), amount of intravenous contrast (215 mL vs 164 mL), and preoperative (1.12 vs 1.26 mg/dL), and postoperative (1.15 v. 1.31 mg/dl) creatinine levels were similar in the concomitant vs staged group, respectively (P > .05 for all factors). More sensitive markers of renal insufficiency such as creatinine clearance were not measured. In the concomitant group, 25% (4/16) of patients reported significant symptoms of buttock claudication ipsilateral to the embolized IIA, which resolved after a mean of 8.8 months (range, 1 to 15 months) vs no cases (0/8) in the staged group (P = .02048). One patient in the staged group developed ischemic colitis, which was treated conservatively. Coil embolizations that were performed as staged procedures were all done on an outpatient basis. All 24 patients were admitted the day of the EVAR and were discharged the next day, except one patient in the concomitant group was discharged the second day after the procedure, and one patient in the staged group was discharged 7 days after the procedure. Despite concern of prolonged operative time and the amount of contrast needed to perform concomitant IIA embolization and EVAR, our results showed that in patients with normal renal function, concomitant unilateral IIA embolization in the setting of EVAR was safe and effective and associated with shorter hospitalization compared with staged procedures. The disadvantage of a concomitant procedure is an increased likelihood of transient buttock claudication, but the small number of patients in this series prohibits definite conclusions about this complication. The concomitant procedure may be preferable for infirm patients with normal renal function who would be greatly inconvenienced by two procedures.