© 2016 Wiley Periodicals, Inc. Background Although mortality associated with atrial fibrillation (AF) has been reported to decrease over prior decades, the mortality risk of asymptomatic, nonhospitalized AF has not been examined. Hypothesis Asymptomatic, nonhospitalized AF is associated with an increased risk of death. Methods This analysis included 25 976 participants (mean age, 65 ± 9.4 years; 55% female; 38% black) from the Reasons for Geographic And Racial Differences (REGARDS) study. Atrial fibrillation was detected on the baseline electrocardiogram (ECG AF) or by self-reported history. Atrial fibrillation unawareness was defined as present if ECG evidence of the arrhythmia was detected but no self-reported history was reported. All-cause mortality was confirmed during follow-up through March 31, 2014. Results A total of 2208 (8.5%) participants had AF at baseline (ECG: n = 371/17%; self-reported: n = 1837/83%). Over a median follow-up of 7.6 years, 3481 deaths occurred. In a multivariable Cox regression model, AF was associated with a 32% increased risk of mortality (95% confidence interval [CI]: 1.19-1.46). Risk of death was higher among those with ECG AF (hazard ratio: 1.71, 95% CI: 1.42-2.07) compared with self-reported cases (hazard ratio: 1.15, 95% CI: 1.03-1.29). Those who were unaware of their AF diagnosis had a 94% increased risk of death (95% CI: 1.50-2.52) compared with AF participants who were aware of their diagnosis. Conclusions Asymptomatic, nonhospitalized AF is associated with an increased risk of mortality in the general population. Mortality is higher in those with ECG-confirmed cases and among those who are unaware of their diagnosis.