Thirty eight cases of moyamoa disease, 21 children, 17 adults were encountered during a 16-year period at Yonsei University Medical Center. Clinical manifestations, together with computed tomography (CT) and angiographic findings were analyzed with a review of the literature. The mean age was 6.3 +/- 3.5 years in children and 36.8 +/- 9.9 years in adults. The majority of attacks occurred in spring in both adults and children. The most common chief complaint on admission was hemiparesis followed by convulsion in children, while in adults, loss of consciousness was most common followed by headache. Of transient neurologic deficits, hemiplegia was most common in children, while cranial nerve involvement was common in adults. Hemiplegia, also was the most common permanent neurologic manifestation in children, while hemiparesis and intellectual deterioration were the most common in adults. Of the children, 90.6% showed infarction on CT, while 88.2% of adults had hemorrhage. Bilateral occlusion of the carotid arteries was the most common site of lesions in both adults and children on cerebral angiogaphy.