In 16 children treated by continuous ambulatory peritoneal dialysis (CAPD) recombinant human erythropoietin was administered intraperitoneally for the treatment of renal anaemia. The mean treatment period was 8.3 months. Mean haemoglobin values increased from 4.9 mmol/l at start of therapy to 6.2 after 6 months. While 11 out of 16 children needed a total of 22 transfusions during the 6 months prior to therapy, no transfusions were needed after initiation of therapy. Patients started with a dose of 300 units/kg per week. After 6 months of therapy, the mean dose was 370 and after 12 months 279 units/kg per week. No major side-effects were observed. The incidence of peritonitis was not increased. We conclude that intraperitoneal administration of erythropoietin is effective in the treatment of renal anaemia in children treated by CAPD.