Recombinant human erythropoietin (rHuEPO) is an effective treatment for the anemia of chronic renal failure. However, adequate availability of iron is necessary for an optimal response. We prospectively evaluated the effect of an intravenous iron protocol in a pediatric hemodialysis unit. Patients with either a serum ferritin less than 150 ng/ml or transferrin saturation (TSAT) less than 20% received intravenous iron dextran during ten consecutive dialysis sessions. The administration of rHuEPO was adjusted using a protocol designed to maintain patient hematocrit between 33% and 36%. Thirteen courses of intravenous iron were evaluated. Patients received 4 mg/kg of iron dextran (maximum of 100 mg) during each of ten consecutive dialysis sessions. In 12 cases there was a decrease in rHuEPO use 2 months after completing the course of intravenous iron. The mean rHuEPO dose decreased from 3,784 units to 2,115 units (P<0.005). Based on the criteria of response to intravenous iron, a percentage iron saturation of less than 20% had a high specificity for detecting iron deficiency. All patients who received a course of intravenous iron had a TSAT less than 20%. The measurement of serum ferritin was less useful in our patients.