Background: Moyamoya disease develops mostly in Asian countries including Japan, Korea, mainland China and Taiwan. However, there was few detailed demographic and clinical data about Chinese patients with moyamoya disease. Here we describe the clinical features, surgical treatment, and long-term outcome of adults with moyamoya disease treated at a single institution in China. Methods: Our cohort included 470 adult patients with moyamoya disease. The demographic and clinical characteristics were obtained by retrospective chart review and long-term outcome was evaluated using the stroke status. Univariate and multivariate logistic regression analyses were performed to determine risk factors for postoperative morbidity and functional outcome. Risk of subsequent stroke was determined using the Kaplan-Meier method and Cox regression was used to determine risk factors for postoperative or subsequent strokes. Results: The median (range) age for the onset of symptoms was 36.8 (18 to 59) years. The ratio of female to male patients was 1:1(231/239). Familial occurrence of moyamoya disease was 2.3%. The most common initial symptom was a cerebral ischemic event. The incidence of postoperative ischemic events or hemorrhage was 5.9% (9.8% of patients). Older age of symptom onset, PCA involvement and present of TIA were identified as predictors of adverse postoperative events. The Kaplan-Meier estimate stroke risk was 10.1% in the first 2 years, and the 5-year-Kaplan-Meier risk of stroke was 13% after surgery for all patients treated with surgical revascularization. Older age of symptom onset, PCA involvement, and present of TIA were identified as predictors of postoperative or subsequent strokes. Overall, 73.2% of patients had an independent life with no significant disability and the strongest predictor being the preoperative mRS score. Conclusion: Clinical characteristics of adult moyamoya disease in China are different from that in other Asian countries. EDAS in adult patients with moyamoya disease carries a low risk, is effective at preventing future ischemic events, and improves quality of life.