Anemia is a common comorbidity in heart failure (HF), and is associated with increased morbidity and mortality. However, it remains unclear whether anemia is merely a marker of poor prognosis or whether anemia itself confers risk. The pathogenesis of anemia in HF is multifactorial. Iron deficiency also confers risk in HF, either with or without associated anemia, and treatment of iron deficiency improves the functional status of patients with HF. An ongoing large clinical trial studying the use of darbepoetin-alfa in patients with anemia and systolic HF is expected to provide information that should improve our understanding of anemia in HF.