OBJECTIVES: This is a randomized controlled study of anemic patients with severe congestive heart failure (CHF) to assess the effect of correction of the anemia on cardiac and renal function and hospitalization. BACKGROUND: Although mild anemia occurs frequently in patients with CHF, there is very little information about the effect of correcting it with erythropoietin (EPO) and intravenous iron. METHODS: Thirty-two patients with moderate to severe CHF (New York Heart Association [NYHA] class III to IV) who had a left ventricular ejection fraction (LVEF) of ≤40% despite maximally tolerated doses of CHF medications and whose hemoglobin (Hb) levels were persistently between 10.0 and 11.5 g% were randomized into two groups. Group A (16 patients) received subcutaneous EPO and IV iron to increase the level of Hb to at least 12.5 g%. In Group B (16 patients) the anemia was not treated. The doses of all the CHF medications were maintained at the maximally tolerated levels except for oral and intravenous (IV) furosemide, whose doses were increased or decreased according to the clinical need. RESULTS: Over a mean of 8.2 ± 2.6 months, four patients in Group B and none in Group A died of CHF-related illnesses. The mean NYHA class improved by 42.1% in A and worsened by 11.4% in B. The LVEF increased by 5.5% in A and decreased by 5.4% in B. The serum creatinine did not change in A and increased by 28.6% in B. The need for oral and IV furosemide decreased by 51.3% and 91.3% respectively in A and increased by 28.5% and 28.0% respectively in B. The number of days spent in hospital compared with the same period of time before entering the study decreased by 79.0% in A and increased by 57.6% in B. CONCLUSIONS: When anemia in CHF is treated with EPO and IV iron, a marked improvement in cardiac and patient function is seen, associated with less hospitalization and renal impairment and less need for diuretics.