A case of Moyamoya disease associated with basilar aneurysm was reported. This case was rare in that it developed from subarachnoid hemorrhage attributable to rupture of basilar aneurysm. The pathological findings of the intracranial blood vessels were almost identical to the findings presented in previous reports. In the vertebral basilar artery system, a remarkable intimal thickening of the intimal cushion type was observed on the side opposite to the origin of the aneurysm. This finding in light of its position was possibly implicated in the formation of cerebral aneurysm in view of the irregularity in blood flow at that site. In the study of the blood vessels of the entire body, slight localized thickening of the intima was observed in the coronary artery, aorta, common carotid artery, renal artery, and common iliac artery, suggesting a possible relation with systemic disease
