The majority of neonates with Rh-isoimmunization develops late anemia between the second and the sixth week of life. We report the effectiveness of recombinant human erythropoietin (rHuEPO) in preventing late anemia in 25 intrauterine and nonintrauterine-transfused neonates. The neonates were treated from 11+/-4 days after birth to 26+/-14 days (400 U/kg/d of rHuEpo, administered subcutaneously). During rHuEpo therapy, vitamin E, calcium folinate, and iron maltose were administered intramuscularly on a daily basis. Hematocrit, platelet, and neutrophil counts did not differ significantly before and after 21-days therapy. However, average values for reticulocyte showed a significant increase. The hematocrit values in the non-intrauterine transfusion (IUT) group increased progressively from the beginning to the end of the treatment, whereas that in the IUT group remained stable. Reticulocyte count increased during treatment in both groups, but it was significantly elevated in the non-IUT group only. Moreover, we observed that only neonates transfused with IUTs needed transfusions before and after treatment. This study suggests the effectiveness of rHuEpo therapy in the treatment of neonates with Rh-isoimmunization and it highlights how IUTs decrease the neonatal response efficacy. Larger, better if multicentric, randomized controlled trial are needed to definitely state whether rHuEPO safely decreases the incidence of late onset anemia.