The aim of the study was to assess the factors associated with the anticoagulation treatment in patients with atrial fibrillation (AF). A total of 2242 consecutive patients who had been admitted with AF on their electrocardiogram were included in the study. After excluding valvular AF, 1745 patients with nonvalvular AF were analyzed. Mean CHA2DS2-VASc score [cardiac failure, hypertension, age >= 75 (doubled), diabetes, stroke (doubled), vascular disease, age 65 -74 and sex category (female)], frequency of persistent/permanent AF, hypertension, diabetes mellitus (DM), stroke history, body mass index, and left atrial diameter were significantly higher in patients receiving anticoagulant therapy. Stroke history, persistent/permanent AF, hypertension, DM, age, heart failure, and left atrial diameter were independent predictors of warfarin prescription. Labile international normalized ratio was the only independent negative predictor of effective treatment with warfarin. In this study, we demonstrated that stroke history, persistent/permanent AF, hypertension, DM, and left atrial diameter were positive predictors, whereas advanced age and heart failure were negative predictors of oral anticoagulant use in patients with nonvalvular AF.