The physiological stress of anesthesia, hemorrhage, and operation can all contribute to postoperative morbidity and mortality in the patient who has experienced massive trauma. However, the problems of massive transfusion are not insurmountable. More important than achieving an adequate blood pressure in the hemorrhaging patient is the need to reestablish adequate tissue perfusion, thus maintaining oxygen transport and appropriate tissue oxygen consumption. Oxygen consumption will decrease after hemorrhagic shock, reflecting a metabolic deficit at the cellular level, and may contribute to end-organ failure. Through blood transfusion, the oxygen consumptive needs of the tissues can be met. Whether the blood administered is autologous or homologous, no superior medium for oxygen transport is yet available. Close attention to the hazards associated with massive transfusion will result in improved outcome and decreased mortality.