A deficiency of erythropoietin is the major cause of anemia in patients with chronic renal failure. In 1984 Eschbach and co-workers (1) demonstrated that daily injections of erythropoietin-rich plasma corrected anemia in chronically uremic sheep. In the first studies of r-huEPO given to severely anemic hemodialysis patients, all patients showed increments of their reticulocyte counts and hemoglobin concentrations. The need for further blood transfusions was eliminated and hematocrits were restored to normal (2,3).