A 64-year-old female was admitted to the hospital with a history of three previous subarachnoid hemorrhages. Neurological examinations revealed incontinentia urinae, gait disturbance, recent memory disturbance and motor weakness on the left side. Plain X-ray films showed a ring-like calcification in the right frontal region. A plain CT scan showed a ring-shaped iso- and high-density area in the intra hemispheric region, the intra bilateral anterior horn of the lateral ventricle, the intra septum pellucidum, and the intra anterior part of the third ventricle. Left carotid angiography showed a large aneurysmal shadow arising from the anterior communicating artery and another from the left middle cerebral artery. In the venous phase the venous angle was supero-posteriorly shifted, and the septal vein was elevated. She died unexpectedly with a status epilepticus of unknown origin. An autopsy specimen revealed that a giant aneurysm occupied the intra ventricular space, the anterior horn of the lateral ventricle, and the right thalamic region. Also, there was a large berry aneurysm arising from the middle cerebral artery. A coronary section through the giant aneurysm showed a markedly compressed left lateral ventricle, right thalamus, and hypothalamus, while the third ventricle had shifted toward the left side.