One hundred cases of Moyamoya disease were encountered between 1961 and 1980. This report describes the clinical characteristics and emphasizes the angiographic findings and clinical correlation in this disease. Reasons for the differences in clinical and radiological presentation in children versus adults are proposed and a possible pathophysiological mechanism is outlined. Treatment with perivascular sympathectomy and superior cervical ganglionectomy may be useful but more investigation needs to be carried out into the pathogenesis of the disease before more definitive therapy is realized.