Endovascular aortic aneurysm repair (EVAR) is used to treat aorto-iliac and isolated iliac aneurysms in selected patients, and prospective studies have shown advantages compared with open surgical repair, mainly in the first years of follow-up. Although this technique produces good results, anatomic issues (such as common iliac artery ectasia or an aneurysm that involves the iliac bifurcation) can make EVAR more complex and challenging and can lead to an inadequate distal seal zone for the stent-graft. Inadequate distal fixation in the common iliac arteries can lead to a type Ib endoleak. To avoid this complication, one of the most commonly used techniques is unilateral or bilateral internal iliac artery occlusion and extension of the iliac limb stent-graft to the external iliac arteries with or without embolisation of the internal iliac artery. However, this occlusion is not without harm and is associated with ischaemic complications in the pelvic territory such as buttock claudication, sexual dysfunction, ischaemic colitis, gluteal necrosis, and spinal cord injury. New endovascular devices and alternative techniques such as iliac branch devices and the sandwich technique have been described to maintain pelvic perfusion and decrease complications, achieving revascularisation of the internal iliac arteries in patients not suitable for an adequate seal zone in the common iliac arteries. These approaches may also preserve the quality of life of treated individuals and may decrease other serious complications including spinal cord ischaemia, ischaemic colitis, and gluteal necrosis, thereby decreasing the morbidity and mortality of EVAR. To assess the effects of internal iliac artery revascularisation versus internal iliac artery occlusion during endovascular repair of aorto-iliac aneurysms and isolated iliac aneurysms involving the iliac bifurcation. The Cochrane Vascular Information Specialists searched the Cochrane Vascular Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library; MEDLINE; Embase; the Cumulative Index to Nursing and Allied Health Literature (CINAHL); and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 28 August 2019. The review authors searched Latin American Caribbean Health Sciences Literature (LILACS) and the Indice Bibliográfico Español de Ciencias de la Salud (IBECS) on 28 August 2019 and contacted specialists in the field and manufacturers to identify relevant studies. We planned to include all randomised controlled trials (RCTs) that compared internal iliac artery revascularisation with internal iliac artery occlusion for patients undergoing endovascular treatment of aorto-iliac aneurysms and isolated iliac aneurysms involving the iliac bifurcation. Two review authors independently assessed identified studies for potential inclusion in the review. We used standard methodological procedures in accordance with the Cochrane Handbook for Systematic Review of Interventions. We identified no RCTs that met the inclusion criteria. We found no RCTs that compared internal iliac artery revascularisation versus internal iliac artery occlusion for endovascular treatment of aorto-iliac aneurysms and isolated iliac aneurysms involving the iliac bifurcation. High-quality studies that evaluate the best strategy for managing endovascular repair of aorto-iliac aneurysms with inadequate distal seal zones in the common iliac artery are needed.