Recent observational data suggest that mild or moderate heart failure is associated with an annual risk of stroke of approximately 1.2%. Indeed, it is possible that the major cause of sudden death in chronic heart failure is not related to arrhythmias, but to vascular occlusion. Anticoagulation may reduce the rate of embolic events, but there is controversy about the mandatory use of antithrombotic therapy for all patients with ventricular dysfunction in sinus rhythm. At present antithrombotic therapy is indicated only in "high risk" subgroups of patients: atrial fibrillation, mobile/protruding/irregular thrombi, acute post-myocardial infarction thrombi or a recent history of thromboembolism. Actually there is no evidence to recommend the use of aspirin to prevent thromboembolism in patients with ventricular dysfunction in sinus rhythm. Further trials of both antiplatelet agents and anticoagulation are sorely needed and we are waiting for the results of large trials such as the WATCH trial (Warfarin and Antiplatelet Therapy in Chronic Heart Failure) and the WARCEF trial (Warfarin Versus Aspirin in Reduced Ejection Fraction). The future appears promising due to the advent of a new oral direct thrombin inhibitor, ximelagatran, with good efficacy and safety profile for the treatment and prevention of thromboembolism.