Elevated circulating levels of fibroblast growth factor 21 (FGF21) are associated with multiple cardiovascular disease (CVD) risk factors and incident events. Previous small cross-sectional studies, mainly in Chinese populations, have suggested FGF21 may play a role in the development of atrial fibrillation (AF). We therefore investigated the relationship of FGF21 levels with incident AF in participants free of clinically apparent CVD at baseline in a large, multi-ethnic cohort.