Although the risk of thromboembolism in chronic heart failure is high even in the absence of atrial fibrillation, the risk to benefit ratio of anticoagulation vs. antiplatelet therapy or no antithrombotic therapy is poorly defined in this population. Post hoc analysis of large therapeutic heart failure trials has estimated the risk of thromboembolism to be between 1 and 4.5%. However, most of these studies have included some patients with atrial fibrillation, and thromboembolism was not a predefined endpoint. At present, the evidence for either anticoagulation or antiplatelet therapy is limited and the results from current large-scale randomized studies are awaited. From the randomized studies carried out thus far, there is a beneficial trend in favour of anticoagulation therapy, with less hospitalization for heart failure compared with patients taking aspirin.