Human recombinant erythropoietin (r-HuEPO, EprexR) was administered to 8 children with chronic renal failure and high transfusion requirement. The hormone was given i.v. 2-3 times per week at the end of the dialysis. The selected initial dose (160 U/kg/week) was gradually raised up to a maximum of 400 U/kg/week. Anaemia normalised by the tenth week. The aimed target haematocrit was 0.33, the average maintenance dose was 250-300 U/kg/week. The absolute reticulocyte count seemed to be a more sensitive indicator of the actual erythropoietin effect than the haematocrit level. No major adverse effects (convulsion, progressive hypertension, thrombosis) were observed during treatment with r-HuEPO. The need for transfusions decreased dramatically, no transfusion was needed following the second week of treatment. The general condition improved substantially. In one hyperimmunized child the cytotoxic antibody titer decreased by 75 per cent.