The aim of this study was to evaluate the 30-day outcome of carotid endarterectomy in patients with contralateral carotid artery occlusion and compare it to that in patients with patent contralateral carotid artery. We compared 2,959 carotid endarterectomies performed in patients with patent contralateral internal carotid artery to 373 carotid endarterectomies performed in patients with occlusion of the contralateral carotid artery in the same institute between 1988 and 2004. Patient demographics, surgical and anesthesiological strategy, perioperative neurological and cardiac events, and deaths were compared. The patients were grouped and analyzed according to the presence or absence of symptoms and to their gender. No significant difference was shown in perioperative cardiological and neurological events and deaths in patients with contralateral carotid occlusion versus patients without contralateral carotid occlusion. Females had significant more neurological events than males, in both the asymptomatic (P < 0.001) and symptomatic (P = 0.02) groups. Concomitant occlusion of the contralateral carotid artery was not associated with increased risk of perioperative cardiological or neurological adverse events. However, female gender was associated with higher risk for adverse neurological events.