Introduction Structural changes in the heart are known risk factors for atrial fibrillation (AF). An association between high-sensitivity cardiac troponin T (hs-cTnT), a marker of myocardial cell damage measured with a high-sensitivity assay, and the risk of AF could have implications for AF risk stratification. Objective To estimate the association between hs-cTnT and the risk of incident AF in the ARIC study, a prospective cohort of middle-aged adults from 4 US communities. Methods Study included 10,584 participants (mean age 62.7 years) free of AF in 1996 to 1998 and followed through 2008. Atrial fibrillation was defined using International Classification of Diseases codes from hospitalizations and death certificates. Participants with undetectable hs-cTnT levels (58%) were assigned the lower limit of measurement (5 ng/L). Net reclassification improvement was used to examine the discriminative ability of hs-cTnT for 10-year AF risk prediction (categories: b5%, 5%-15%, and N15%). Results A total of 920 incident AF cases were observed for 109,227 person-years. After adjustment, a 1-SD difference in ln(hs-cTnT) was associated with a hazard ratio of 1.16 (95% CI 1.10-1.23). Compared with those with undetectable levels, participants with hs-cTnT ≥14 ng/L had a hazard ratio of 1.78 (95% CI 1.43-2.24). Addition of hs-cTnT to known AF predictors did not increase the c statistic appreciably (0.756 vs 0.758) or improve risk stratification (net reclassification improvement 0.4%, 95% CI -1.4% to 2.3%). Conclusions High-sensitivity cTnT level is associated with an increased incidence rate of AF but did not improve risk stratification.