We administered recombinant human erythropoietin (r-hu EPO) to 18 anaemic patients with end-stage renal disease who were undergoing haemodialysis. The recombinant human erythropoietin was given intravenously three times weekly after dialysis, and transfusion requirements, haematocrit, ferrokinetic, reticulocyte responses and urea, creatinine and potassium kinetics were monitored. Over a range of doses between 50 to 90 units per kilogram of body weight, dose-dependent increases in effective erythropoiesis were noted. Of 18 patients receiving effective doses of recombinant human erythropoietin, none needed transfusion any longer and in 2 the haematocrit increased to 35%. Along with the rise in haematocrit, four patients had an increase in blood pressure, and the majority had increases in serum potassium, fibrinogen, leucocyte and reticulocyte counts. Except for transiently increased transaminase levels in one patient, no other organ dysfunction or toxic effect was observed. These results demonstrate that recombinant human erythropoietin is effective, can eliminate the need for transfusions with risks of immunologic sensitization, infection and iron overload, and can restore the haematocrit to normal levels in many patients with anaemia of end-stage renal disease.