Moyamoya Disease is a progressive occlusive cerebrovascular disease of both internal carotid arteries and their branches, with compensatory development of a fine collateral vascular network. The etiology of the disease is unknown; however, several studies have suggested involvement of genetic and environmental factors in its pathogenesis. In children, it causes transient ischemic attacks and cerebral infarction, while bleeding is more frequent in adults. In Japan, where the disease is most frequently observed, the development of magnetic resonance with angiography has allowed diagnosis in asymptomatic Moyamoya Disease. Revascularization surgery is believed to reduce the incidence of new ischemic events and improve long term prognosis in these patients. We present 2 children with Moyamoya Disease treated in our Chmc between 1998 and 2007.