In this study, we investigated the effect of different bypass procedures on postoperative neovascularization in patients with moyamoya disease at Hiroshima University Hospital. Fourteen cerebral hemispheres of seven patients with moyamoya disease were investigated. Five of the 14 hemispheres underwent direct bypass surgery and the remaining 9 underwent indirect bypass. The neovascularization after bypass surgery was evaluated by cerebral angiography. The extent of angiographic neovascularization after direct or indirect bypass surgery was graded as good, fair or poor. Postoperative neovascularization status (good, fair or poor) was compared with the bypass procedure (direct and indirect bypass). Good neovascularization was observed in 8 hemispheres and the remaining 6 had poor neovascularization. Direct bypass surgery was significantly more effective for angiographic neovascularization than the indirect procedure in moyamoya patients (chi2-test, p<0.05). Therefore, we concluded that the direct bypass procedure is a better choice for moyamoya disease as evidenced by angiographic neovascularization.