Acute subdural haematoma (SDH) in association with aneurysmal subarachnoid hemorrhage (SAH) from a pericallosal artery aneurysm is extremely rare. Although rare, failure to diagnose such an uncommon aneurysm can lead to fatal errors in surgical planning for SDH. A 73-years old woman was brought to the emergency department complaining of acute onset severe headache and depressed level of consciousness. There was no history of trauma. On neurological examination, the patient was unconscious, unresponsive to painful stimuli. Cranial computed tomography (CT) demonstrated a right holo-hemispheric SDH, relatively little SAH and transtentorial herniation. Suspicion led to the demonstration of two aneurysms in the anterior cerebral artery (ACA) using quick CT-angiography. The patient was taken for emergency surgery for successful distal ACA aneurysm clipping as well as SDH evacuation. The patient had an uneventful postoperative course with good recovery. We conclude that a careful examination of basal radiological investigations is of vital importance to decrease the operative risk of mortality and morbidity.