The association between anemia and chronic renal failure has been recognized since the early 19th century. With the introduction of regular dialysis treatment, an understanding of all aspects of this uremic complication has become of great importance, including an appreciation of the hazards of multiple blood transfusions. This analysis of hemoglobin levels and transfusion requirements in 84 dialysis patients focuses specific attention on hemolytic mechanisms, blood loss, and the effect of bilateral nephrectomy on erythropoiesis. Because no replacement for renal erythropoietin is available, particular attention must be paid to less important, but partially correctable factors that contribute to anemia. Blood transfusion requirements can then be reduced to a minimum, together with the risks of hypersplenism, hepatitis, and sensitization of the patient to alloantigens.