We performed magnetic resonance angiography (MRA) in 12 children with a suspected or angiographically proven moyamoya disease. MRA was performed by the three-dimensional, time-of-flight technique and, successfully depicted the primary abnormalities in the distal carotid arteries in 10 out of the 12 patients. In the other two patients, poor visualization of the intracranial vasculature strongly suggested the presence of the disease. On MRA, moyamoya vessels were visible in eight patients. The presence of anastomoses was also confirmed by MRA in seven of the 10 patients who had undergone encephalo-duro-arterio-synangiosis. Our findings suggest that MRA may be the tool of choice for selecting patients to undergo conventional angiography. However, establishing a definite diagnosis still requires some improvements in the delineation of the fine vasculature.