['Current strategies for avoiding atrial fibrillation (AF) are of limited value. We aim to assess the relationship between omega-3 fatty acids (n-3 PUFA) and AF occurrence in post-myocardial infarction (MI) patients.', 'A population study, linking hospital discharge records, prescription databases, and vital statistics, was conducted and included all consecutive patients with MI (ICD-9: 410) in six Italian local health authorities over a 3-year period. A propensity score (PS)-based, 5-to-1, greedy 1:1 matching algorithm was used to check consistency of results. Sensitivity analysis was performed to assess the robustness of findings.', 'N-3 PUFA reduced the relative risk of the hospitalization for AF [hazard ratio (HR) 0.19, 95% CI 0.07-0.51] and was associated with a further and complementary reduction in all-cause mortality (HR 0.15, 95% CI 0.05-0.46). PS-based matched analysis and sensitivity analysis confirmed the main results.'] Does omega-3 fatty acid supplementation reduce one-year risk of atrial fibrillation in patients hospitalized with myocardial infarction?