Recombinant human erythropoietin (rhEPO) used for the treatment of children with renal anemia is an effective stimulus of erythroid proliferation and differentiation. The increases of reticulocytes and of the hematocrit values give the possibility to renounce further blood transfusions in dialysis patients. There are no beneficial in vivo effects of rhEPO on the glutathione status and on the nucleotide contents of red blood cells. Therefore, indices for stabilizing effects of rhEPO on the circulating red blood cells cannot be due to glutathione and nucleotide metabolism.