Moya Moya disease is a rare chronic occlusive cerebrovascular disease of unknown etiology for which no effective treatment has been found. This disease has distinct angiographic features. These include 1) Either marked stenosis or complete occlusion of the distal internal carotid arteries. 2) Poorly visualized anterior and middle cerebral arteries at their proximal portions. 3) Well developed fine vascular networks at the base of the brain. These features are peculiar findings of this disease and the clue of the occlusion and its collateral circulation. Authors reported 3 cases of moya moya disease is discussed.