Background Warfarin is efficacious for ischemic stroke prevention in intermediate- to high-risk patients with atrial fibrillation; thus, warfarin is the recommended treatment according to evidence-based guidelines. Objective This prospective study evaluated the reasons for under-utilization of warfarin in Chinese patients with non-valvular atrial fibrillation (NVAF). Setting The People’s Hospital of Henan Province of Zhengzhou City, which is a 3900-bed tertiary-care teaching institution. Methods We extracted data from an existing patient database. Patients at risk for thromboembolism were categorized based on CHA2DS2-VASc [congestive heart failure, hypertension, age ≥75 (doubled), diabetes, prior stroke (doubled), vascular disease, age 65–74 years, and sex category (female)] scores. Main outcome measure The percent of warfarin utilization was estimated in recruited patients. Any demographic and clinical factors associated with warfarin under-utilization were identified using a logistic regression model. Results Among the patient sample (n = 612), 569 patients had a CHA2DS2-VASc score of ≥1. At presentation, warfarin under-utilization was estimated to be 27.1 %. Only 120 patients (25.1 %) considered to be at the highest risk were prescribed warfarin. Binary logistic regression analysis indicated that previous stroke, age ≥75 years, and anti-platelet therapy were associated with warfarin under-utilization. Conclusion Patients with CHA2DS2-VASc scores ≥1 who were admitted with NVAF were under prescribed warfarin, and 138 patients were not treated with either warfarin or other antithrombotic therapies. In conclusion, a more aggressive approach for stroke prevention in NVAF patients is required.