Several epidemiological studies have demonstrated an association between HF and anemia and correlation of increased risk for mortality and hospitalization with low hemoglobin in patients with HF. Earlier single-center interventional studies suggest that meaningful clinical benefits may be achieved by raising hemoglobin concentration in patients with symptomatic HF and anemia. Data from Amgen's completed phase 2 multi-center studies support this hypothesis and show that darbepoetin alfa is well tolerated in patients with symptomatic left ventricular systolic dysfunction and anemia and effectively raises hemoglobin. The pivotal phase 3 Study 20050222 RED-HF Trial is evaluating the effect of treatment with darbepoetin alfa on the composite risk of all-cause mortality or hospitalization for worsening HF in patients with symptomatic left ventricular systolic dysfunction and anemia. This study also evaluates the effect of darbepoetin alfa treatment on all-cause death, on cardiovascular death or hospitalization for worsening HF, and on patient-reported quality-of-life outcomes.