Background:Atrial fibrillation (AF) is a common arrhythmia in the elderly, and causes complications such as cardioembolic stroke. Serum high-sensitivity C-reactive protein (hs-CRP), a marker of systemic inflammation, has been reported to be a risk factor for developing AF in Western countries. However, few community-based studies have examined this issue in general Asian populations.Methods and Results:A total of 2,510 community-dwelling Japanese participants aged ≥40 years without a history of AF were divided into 4 groups according to the sex-specific quartiles of serum hs-CRP concentrations (Q1, lowest and Q4, highest) and followed up for 24 years. The hazard ratios and their 95% confidence intervals for the development of AF were estimated using a Cox proportional hazards model. During the follow up, 234 subjects developed AF. The risk of AF increased significantly with elevating serum hs-CRP levels after adjustment for potential confounding factors (hazard ratio 95% confidence interval, Q1, 1.00 reference; Q2, 1.26 0.83–1.92; Q3, 1.77 1.18–2.66; and Q4, 1.89 1.24–2.86; P for trend <0.001).Conclusions:The study findings suggest that elevated serum hs-CRP levels are an independent risk factor for the development of AF in a general Japanese population.