The renal glycoprotein hormone erythropoietin is an essential growth factor for the erythrocytic progenitors in the bone marrow. Erythropoietin deficiency is the main cause of the anemia in chronic renal failure. Genetical engineering has made it possible to produce recombinant human erythropoietin (rhu-Epo) in CHO cell cultures as a pharmaceutical compound. Endogenous and recombinant erythropoietin are similar with respect to their biological and chemical properties (M(r) 30,400 Da, protein content 60%, 165 amino acids, 4 carbohydrate side chains). With few side-effects, rhu-Epo corrects the anemia of predialysis and dialysis renal failure patients. In addition, rhu-Epo treatment may reduce the need for blood transfusion in other types of anemias, including those of rheumatoid arthritis, AIDS, malignant diseases and major surgical procedures. However, rhu-Epo has not been approved as yet for treatment of non-renal anemias in Germany.