Objective: Patients of aorto-iliac aneurysms who undergo endovascular aortic repair (EVAR) require internal iliac artery (IIA) occlusion with coil embolization and its coverage with the stent graft to prevent type II endoleak after extending the endograft into the external iliac artery. However, it has become well recognized that IIA occlusion cause buttock claudication and other various sequelae due to pelvic ischemia. We retrospectively analyzed IIA occlusion outcomes. Methods: From October 2008 to February 2015, 71 patients with aorto-iliac aneurysms underwent IIA occlusion prior to EVAR. The relationship between pelvic circulation and symptom of pelvic ischemia was studied. Results: Buttock claudication occurred in 17 patients (22.9%) of all. Eight patients (14.8%) in unilateral IIA occlusion group (54 patients) and nine patients (52.9%) in bilateral IIA group (17 patients) had sequelae of claudication. The sacrifice of the communication of superior gluteal artery (SGA) and inferior gluteal artery (IGA) led to buttock claudication in 18 (64.3%) of 28 limbs. Instead, only 4 of 60 limbs had buttock claudication, when we preserved the communication between SGA and IGA. In all patients, staged treatment of aorto-iliac aneurysms with IIA occlusion and EVAR were done successfully without pelvic ischemic complications except for buttock claudication, and postoperative CT scanning showed no endoleakage. Conclusion: IIA occlusion prior to EVAR is recognized as a safe and reasonable strategy. It is emphasized that preservation of the communication of SGA and IGA is important to prevent buttock claudication. (This is a translation of Jpn J Vasc Surg 2016; 25: 240-245.).