New light has recently been shed on transfusion therapy. Early recurrence of cancer, ill effects on the immune system and increased incidence of postoperative infections have all been suggested as possible complications of overenthusiastic transfusion therapy. The need for perioperative transfusions has been overestimated in the past, since new physiological investigations show that a hemoglobin level of 8 g/100 ml can be tolerated at elective surgery provided that the patient is normovolemic and normothermic. Neither has the danger of virus contamination been entirely eliminated. With this in mind, blood component therapy, giving erythrocytes and plasma components according to documented need, has been started. The article describes our institution's suggested policy for transfusion therapy and volume treatment in elective and trauma surgery.