We prospectively examined the association between alcohol consumption and risk of atrial fibrillation or flutter among 47,949 participants (mean age 56 years) in the Danish Diet, Cancer and Health Study. During follow-up (mean 5.7 years) atrial fibrillation or flutter developed in 556 subjects (374 men and 182 women). We found that consumption of alcohol was associated with an increased risk of atrial fibrillation or flutter in men. In women, moderate consumption of alcohol did not seem to be associated with an increased risk of atrial fibrillation or flutter.