To clarify the efficacy of direct revascularization to prevent rebleeding of moyamoya disease, we retrospectively analyzed 48 patients who had an episode of intracranial bleeding. We performed STA-MCA anastomosis on 74 hemispheres in 46 patients. Of the 55 hemispheres which had been studied by postoperative angiography, 38 showed regression of the moyamoya vessels and did not rebleed. Postoperative rebleeding was counted 9 times; 4 occurred in the operated hemispheres and 5 did in the non-operated ones. All of tile 4 hemispheres which had been revasculized but rebled did not show regression of the moyamoya vessels. Direct revascularization has a potential to reduce hemodynamic stress on weak moyamoya vessels and is effective for the prevention of rebleeding, but in limited cases.