OBJECTIVE When abdominal aortic aneurysms and common iliac artery (CIA) aneurysms undergo concomitant endovascular repair, endograft limb extension into the external iliac artery is often necessary. Usually, the internal iliac artery (IIA) is coil embolized in such a case to prevent endoleak. It has been our practice to coil embolize the IIA only in cases where there is not adequate stent graft seal in the CIA immediately proximal to the IIA origin (effectively sealing the entire IIA origin). In this study, we evaluated the outcomes of this approach. METHODS We retrospectively reviewed 204 consecutive endovascular abdominal aortic aneurysm repairs at Dartmouth-Hitchcock Medical Center from 1996 to 2001. Computed tomographic angiography with three-dimensional reconstruction was the primary preoperative imaging modality, and the decision to cover the IIA without concomitant coil embolization was based before surgery on the presence of adequate graft oversizing (> or =10% to 15%) in the most distal 5 mm of CIA and 15 mm of proximal external iliac artery, respectively. RESULTS The IIA was occluded 33 times in 31 patients. In 22 cases (67%), the IIA was covered without coil embolization (COVER group). The remaining 11 patients (33%) with inadequate graft oversizing in the CIA underwent IIA coil embolization (COIL group). The follow-up periods for the COVER and COIL groups were 19 +/- 2 months and 10 +/- 3 months, respectively. All operations in both groups were technically successful without evidence of endoleak at completion angiography. No endoleaks, graft migrations, or aneurysm enlargements were associated with the covered or coiled IIAs during the follow-up period. No clinical sequelae were seen in the COVER group, with the exception of buttock claudication in six patients (27%) that resolved completely in five patients. In the COIL group, five patients (45%) had buttock claudication. In addition, one case of buttock necrosis and one case of ischemic neuropathy occurred in the COIL group. CONCLUSIONS Covering the IIA without coiling effectively excluded the CIA aneurysm in every case and was associated with a low incidence rate of complications compared with coil embolization. With detailed preoperative imaging and patient selection, IIA coil embolization may not be necessary in as many as two thirds of patients who need IIA occlusion.