The incidence of atrial fibrillation is greater in men than in women, but this gap closes with advancing age. More women with atrial fibrillation have underlying valvular disease, and more men with this condition have underlying coronary artery disease. Atrial fibrillation increases mortality and the incidence of stroke in both sexes. However, women in particular (especially those over 75 years old) may be at increased risk for embolism and long-term mortality. Gender is also an important feature affecting the selection of antiarrhythmic drugs for atrial fibrillation, because women are more likely to develop drug-induced arrhythmias. Stroke prevention with anticoagulation in chronic atrial fibrillation is a priority in both men and women; however, women derive the most benefit from it.