Background & aims: Whether high intakes of fish and long-chain omega-3 polyunsaturated fatty acids (PUFAs) reduce the risk of atrial fibrillation (AF) remains uncertain. Thus, we aimed to evaluate the associations of total fish, types of fish, and omega-3 PUFA intake with AF incidence in a large prospective study. Methods: We used data from the Cohort of Swedish Men and the Swedish Mammography Cohort to examine the associations of fish consumption and long-chain omega-3 PUFA intake with AF incidence. At baseline, information on fish and omega-3 PUFA intakes was available from 72,984 men and women, aged 45-83 years, without cardiac disease. Cases of AF were identified through linkage with the Swedish National Patient Register. Multivariable-adjusted relative risks were estimated with the use of Cox proportional hazards models. Results: Over a follow-up period of 12 years, 6095 participants (3595 men and 2500 women) developed AF. Intakes of total fish, fatty fish (herring/mackerel and salmon/whitefish/char), and long-chain omega-3 PUFAs were not associated with AF incidence after adjustment for other risk factors. However, high consumption of lean fish (cod/saithe/fish fingers) was associated with a lower risk; multivariable relative risk of AF for >= 3 servings/week compared with never consumption was 0.79 (95% confidence interval, 0.65-0.95). Conclusions: These findings do not support a beneficial association of fatty fish or omega-3 PUFA intake with incident AF. The association between lean fish consumption and AF risk warrants further investigation. (C) 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.