Atrial fibrillation (AF) is the most common cardiac arrhythmia and an important independent stroke risk factor, especially in the elderly. This article provides the reader with an overview as well as an update on primary and secondary stroke prevention strategies in patients with AF. Vitamin K antagonists remain the cornerstone therapy in AF patients at high risk of stroke. Both aspirin monotherapy and the combination of aspirin and clopidogrel are inferior to vitamin K antagonists in patients with AF. The new direct thrombin inhibitor dabigatran is at least as effective as warfarin and leads to a significant and clinically relevant decrease in hemorrhagic stroke and intracranial bleeds. Interventional therapies such as percutaneous closure of the left atrial appendage or radiofrequency catheter ablation have not yet been proven to decrease the stroke risk in patients with AF.