We investigated the risk of stroke associated with renal dysfunction and the impact of warfarin therapies in Chinese patients with nonvalvular atrial fibrillation (NVAF). Information was collected on age, sex, height, weight, type of atrial fibrillation, and serum creatinine within the previous 6 months, together with the variables needed to calculate the CHADS(2) score. For patients not taking warfarin, reasons why not were recorded. Three thousand seventeen eligible patients with NVAF, mean (1 standard deviation [SD]) age of 67.7 (13.0) years, from 50 Chinese hospitals were included from May 2012 to October 2012, with a mean (1SD) CHADS(2) score of 2.0 (1.5). Of these, 58.3% were male and 86.2% were at high risk of stroke with a CHADS(2) score 1. Only 42.6% were on warfarin, and 22.5% of the patients had moderate or severe renal impairment (estimated glomerular filtration rate < 60 mL/min/1.73 m(2)). After adjustment for the CHADS(2) score, renal dysfunction remained moderately but significantly associated with the risk of stroke/TIA (odds ratio = 1.005, 95% confidence interval: 1.002-1.009, P = .002). There was, however, no significant difference in anticoagulant usage between patients with or without impaired renal dysfunction. The most common anticoagulant concerns were the low proportion of patients with regular international normalized ratio monitoring (43.0%) and the risk of bleeding (33.3%). Renal impairment was common and independently associated with the risk of cerebrovascular embolism in Chinese patients with NVAF but not independently related to underuse of anticoagulant treatment.