To compare two modalities of iron supplementation for the preoperative stimulation of erythropoiesis using recombinant human erythropoietin (rhEPO), 12 adults in normal hemoglobin and iron status due for elective surgery were randomized to rhEPO 200 U/kg body weight subcutaneously twice weekly combined with either iron sucrose 200 mg intravenously twice weekly or iron sulfate 160 mg/day orally, for 3 weeks preoperatively. Efficacy was measured by the increases over baseline in hemoglobin, reticulocyte count, and ferritin determined 3 days before surgery; preoperative reticulocyte count and ferritin were significantly higher with intravenous iron, whereas the only significant intragroup increases in hemoglobin between time points also occurred in this group. Intravenous iron significantly boosts the hematopoietic response to rhEPO and prevents iatrogenic iron depletion in otherwise healthy candidates for elective surgery.