This randomized study assessed if intravenous iron improves hemoglobin (Hb) response and permits decreased epoetin dose in anemic (Hb 9-11 g/dl), transfusion-independent patients with stainable iron in the bone marrow and lymphoproliferative malignancies not receiving chemotherapy. Patients (n=67) were randomized to subcutaneous epoetin beta 30 000 IU once weekly for 16 weeks with or without concomitant intravenous iron supplementation. There was a significantly (P<0.05) greater increase in mean Hb from week 8 onwards in the iron group and the percentage of patients with Hb increase >or=2 g/dl was significantly higher in the iron group (93%) than in the no-iron group (53%) (per-protocol population; P=0.001). Higher serum ferritin and transferrin saturation in the iron group indicated that iron availability accounted for the Hb response difference. The mean weekly patient epoetin dose was significantly lower after 13 weeks of therapy (P=0.029) and after 15 weeks approximately 10 000 IU (>25%) lower in the iron group, as was the total epoetin dose (P=0.051). In conclusion, the Hb increase and response rate were significantly greater with the addition of intravenous iron to epoetin treatment in iron-replete patients and a lower dose of epoetin was required.