Cerebral hyperperfusion syndrome is a well-recognized and potentially fatal complication of carotid revascularization. However, the occurrence of non-aneurysmal subarachnoid hemorrhage as a manifestation of cerebral hyperperfusion syndrome post-carotid endarterectomy is uncommon. We report a case of a patient who presented with headache following carotid endarterectomy for a critically occluded common carotid artery. This progressed to deteriorating consciousness and seizures. Investigations revealed a left cortical non-aneurysmal subarachnoid hemorrhage. Non-aneurysmal subarachnoid hemorrhage is a rare post-operative complication of carotid endarterectomy. Immediate management with aggressive blood pressure control is key to prevent permanent neurological deficits. Cerebral hyperperfusion syndrome (CHS) after carotid revascularization procedures is an uncommon and potentially fatal complication. Pathophysiologically it is attributed to impaired autoregulatory mechanisms and results in disruption of cerebral hemodynamics with increased regional cerebral blood flow (Cardiol Rev 20:84-89, 2012; J Vasc Surg 49:1060-1068, 2009). The condition is characterized by throbbing ipsilateral frontotemporal or periorbital headache. Other symptoms include vomiting, confusion, macular edema, focal motor seizures with frequent secondary generalization, focal neurological deficits, and intraparenchymal or subarachnoid hemorrhage (SAH) (Lancet Neurol 4:877-888, 2005). The incidence of CHS varies from 0.2% to 18.9% after carotid endarterectomy (CEA), with a typical reported incidence of less than 3% in larger studies (Cardiol Rev 20:84-89, 2012; Neurosurg 107:1130-1136, 2007). Uncontrolled hypertension, an arterially isolated cerebral hemisphere, and contralateral carotid occlusion are the main risk factors (Lancet Neurol 4:877-888, 2005; J Neurol Neurosurg Psychiatry 83:543-550, 2012). We present a case of non-aneurysmal SAH after CEA, with focus on its presentation, risk factors, and management.