Background and Objectives : Atrial fibrillation (AF) is the most common significant arrhythmia in the general population, and it is associated with increased cardiovascular morbidity and mortality. The incidence of and the risk factors for new- Subjects and Methods : We retrospectively analyzed 16,568 adults (median age 49 years, 10,685 males and 5,883 females) who had repeatedly received scree-ning tests for general health at the Health Promotion Center, Samsung Medical Center in Korea betwen March, 2001 and June, 206 (mean follow up duration: 44 months). Results: Sixty one cases had new-onset AF noted on the electrocardiogram (ECG). On the univariate analysis, age, male gender, a history of coronary artery disease and fibrinogen, and left atrium enlargement sen on ECG at baseline were significantly asociated with new-onset AF. After multivariable adjustment, the independent risk factors for predicting new-onset AF were male gender [odds ratio (OR): 3.356, 95% confidence interval (CI): 1.168-9.643, p= 0.025] and a history of coronary artery disease (OR: 4.657, 95% CI: 1.703-12.737, p= 0.003). Conclusion : The risk factors for predicting new-onset AF in persons who (Korean Circ J 2007 ;37:609-615)