Background The mortality of stroke patients is strongly affected by medical complications.However,there are limited data investigating the effect of in-hospital medical complications on the dependency of stroke patients worldwide.We prospectively and systematically investigated the effect of medical complications on dependency of patients at 3,6 and 12 months after stroke using the China National Stroke Registry (CNSR).Methods This prospective cohort study collected data of patients age ＞18 years with acute ischemic stroke in 132 clinical centers distributed across 32 provinces and four municipalities (including Hong Kong region) of China,from September 2007 to August 2008.Data on medical complications,dependency and other information were obtained from paper-based registry forms.Medical complications associated with stroke outcomes were assessed using multivariable Logistic regression.Results Of 11 560 patients with acute ischemic stroke,1826 (15.80％) presented with in-hospital medical complications.In-hospital medical complications were independent risk factors for dependency of patients at 3 months (adjusted odds ratio (OR) 2.367,95％ confidence interval (CI) 2.021-2.771),6 months (adjusted OR 2.257,95％ CI 1.922-2.650),and 12 months (adjusted OR 1.820,95％ CI 1.538-2.154) after acute ischemic stroke.Conclusion The results demonstrated that the short-term and long-term dependency of acute ischemic stroke patients is significantly associated with in-hospital medical complications in China.