Atrial fibrillation (AF) is one of the most common cardiac arrhythmias, and carries an increased risk of cardiogenic embolism. Oral anticoagulants (OACs) including warfarin and/or non-vitamin K antagonists can prevent the majority of these events. The Saitama AF Registry was a community-based survey of patients with AF in Saitama City, which represents an urban community in Japan. A total of 75 institutions participated in the registry and attempted to enroll consecutive patients with AF from September 2014 to August 2015. The aim of the present study was to examine the clinical characteristics of patients with AF using data of the Saitama AF Registry. In addition, we investigated the difference in clinical characteristics of the patients between small-sized hospitals and large-sized hospitals. A total of 3591 patients were enrolled; 57.7% of all patients were enrolled from small-sized hospitals, whereas 42.3% were from large-sized hospitals. The patients from small-sized hospitals had higher CHADS2 score than those from large-sized hospitals. Approximately, 80% of all patients were treated with OACs, and the prescription rate was higher in patients with CHADS2 score ≥ 2 from both small-sized hospitals and large-sized hospitals. In conclusion, the present study demonstrated an appropriate use of OACs for high-risk patients with CHADS2 score ≥2 in Saitama City regardless of hospital size.