Background. Almost half of endovascular aortic aneurysm repair (EVAR) procedures are performed in hostile anatomy, increasing the risk of procedure related complications such as type IA endoleaks, which may be prevented with the chimney technique in EVAR (ChEVAR). Objective: Our aim is to describe the differential characteristics between EVAR in favorable anatomy and ChEVAR in hostile necks. Materials and methods. A cohort of patients with infrarenal abdominal aortic aneurysms (AAA) that were treated with EVAR or ChEVAR were included. The primary outcome was the incidence of type IA endoleak. Secondary outcomes were the rate of chimney occlusion, reintervention, migration, rupture, acute limb ischemia, sac growth, and aneurysm- related mortality during the follow-up period. Results. With a median follow-up of 11.5 months, 79 patients were treated with EVAR and 21 with ChEVAR. The overall...