The association between serum uric acid (SUA) levels and atrial fibrillation (AF) is currently poorly known. We examined the association between SUA levels and risk of incident AF in patients with type 2 diabetes mellitus. We followed for 10 years a random sample of 400 type 2 diabetic outpatients, who were free from AF at baseline. A standard 12-lead electrocardiography was undertaken annually and a diagnosis of incident AF was confirmed in affected participants by a single cardiologist. Over 10 years, there were 42 incident AF cases (cumulative incidence of 10.5%). Elevated SUA level was associated with an increased risk of incident AF (odds ratio 2.43, 95% confidence interval 1.8 to 3.4, p <0.0001 for each 1-SD increase in SUA level). Adjustments for age, gender, body mass index, hypertension, chronic kidney disease, electrocardiographic features (left ventricular hypertrophy and PR interval), and use of diuretics and allopurinol did not attenuate the association between SUA and incident AF (adjusted odds ratio 2.44, 95% confidence interval 1.6 to 3.9, p <0.0001). Further adjustment for variables that were included in the 10-year Framingham Heart Study–derived AF risk score did not appreciably weaken this association. Results remained unchanged even when SUA was modeled as a categorical variable (stratifying by either SUA median or hyperuricemia), and when patients with previous coronary heart disease or heart failure were excluded from analysis. In conclusion, our findings suggest that elevated SUA levels are strongly associated with an increased incidence of AF in patients with type 2 diabetes mellitus even after adjustment for multiple clinical risk factors for AF.