The evidence evaluating the risk of thrombosis and the efficacy and risk of anticoagulation in patients with systolic heart failure (HF) and normal sinus rhythm is reviewed.Although a subject of investigation for over 50 years, use of anticoagulation in patients with HF remains an area of controversy and clinical debate. While early studies reported variable thromboembolism rates in HF (1.9-42.4 events per 100 patient years), the annual rate from larger and more recent trials ranged from 1% to 3%. The trials evaluating the role of oral anticoagulants to reduce thromboembolism and mortality outcomes in patients with a reduced ejection fraction (EF) have provided ambiguous results. Early studies and post hoc analyses of large clinical trials have demonstrated a reduction in thromboembolic events, risk of stroke, and mortality. In contrast, recent underpowered prospective controlled studies found no benefit in the use of warfarin in patients with systolic HF and normal sinus rhythm. The low-to-moderate risk of thromboembolism in patients with HF and the questionable benefit of anticoagulation need to be weighed against the potential for hemorrhagic complications caused by this therapy. The available data collectively suggest that the risk of using warfarin in patients with reduced EF may outweigh any possible benefit, if one exists at all.Anticoagulation therapy in patients with HF and normal sinus rhythm is not supported by the limited evidence. The benefits of anticoagulation in such patients may not compensate for the relatively high risk of major bleeding caused by the treatment.