Surgical treatment of moyamoya disease Nowadays, it is necessary to prove the efficacy of one treatment when this treatment is accepted to be effective for the disease. To do so, controlled randomized trial is required. As far as moyamoya disease is concerned, there has been not a single trial to establish effective treatment for it. One clinical trial whether direct bypass surgery is effective for adult moyamoya disease with hemorrhagic onset is under way in Japan. Although there are tremendous number of reports on the efficacy of many kinds of surgical treatment for either hemorrhagic or ischemic moyamoya disease, no reports were done by randomization methods. That is, neurosurgeons are continuing to report their surgical methods/results are useful without any control (reference) groups. It is generally believed (without proof) in Japan for moyamoya disease with ischemic onset that: direct bypass is effective for both children and adults. indirect bypass is effective for children, and less effective for adults. Younger patients have poorer prognosis than adults patients do. (Thus, children are more aggressively treated than adults). And, multiple burr-hole surgery is less popular. In many communication with moyamoya patients from abroad, I was surprised to know that multiple burr hole surgery is more common in overseas (Europe and US) than in Japan. There are few reports on natural history of moyamoya disease, but it is interesting to know that one report says prognosis is essentially not different between surgically-treated patients and medically-treated patients. I am not trying to confuse you, but this is the real status of the treatment of moyamoya disease.