Moyamoya disease is an uncommon cerebrovascular disease characterized by progressive steno-occlusive changes in the terminal internal carotid arteries (ICA) and their main branches, associated with the development of moyamoya vessels. The incidence of the disease is high in east Asia, especially in Japan and Korea. The familial form accounts for 10-15%. Moyamoya disease has two age distribution peaks at around 5 and 40years. Most pediatric patients exhibit transient ischemic attacks or infarction. Headache and involuntary movements are serious symptoms associated with pediatric moyamoya disease. MRI and MR angiography (MRA) are useful and non-invasive methods for diagnosing or monitoring moyamoya disease. Cerebral angiography is still the gold standard for a diagnosis, however, it is not mandatory when MRI and MRA show typical findings of moyamoya disease; steno-occlusive changes at the ends of ICA and an abnormal vascular network in the basal ganglia. Other MRI findings have been reported, including T2 shortening in the white matter, the ivy sign on fluid-attenuated inversion recovery (FLAIR) images, and medullary streaks on FLAIR or enhanced T1-weighted images.