The possibility of lower efficacy and the fear of an increased incidence of side effects may explain the reluctance to use recombinant human erythropoietin (r-HuEPO) in patients with impaired renal function who do not yet require dialysis, as well as in transplanted patients with a failing renal allograft. Several recent studies have clearly shown that r-HuEPO is effective in these patient populations and that the doses needed to control anaemia are comparable with or lower than those needed for dialysis patients. When started at a low dose, the risk of severe hypertension is minimal, although in a significant number of patients intensification of the antihypertensive regimen is needed. Moreover, there are no indications that the use of r-HuEPO accelerates the deterioration of residual renal function.