ConstaVac (Stryker, Michigan, U.S.A.), a blood drainage and transfusion device, was applied to transfuse the autologous blood from the wound in 20 patients undergoing total replacement under the spinal anesthesia To evaluate the hemodynamic states, direct arterial blood pressures and central venaus pressures were monitored. Before touniquets release, 500-1000 ml of 10% pentastarch were infused rapidly to prevent hypovolemia until the driining reservior bag was filled to at least 40 ml. During all the procedures the mean arterial pressures were main-tained at about 80 mmHg, even if tbose after the induction of anesthesia were lower tban those at the preanesthetic period. The average amounts of blood loss were 942 ml and 2240 ml in unilateral and simultaneous bilateral surgery, respectively. The average amounts of blood that were salvaged after unilateral and simultaneous bilateral knee arthroplasty were 1113 and 2918 ml, respectively. Until 7 posto-perative days, thrombocytopenia and anemia were developed in one and three cases, respectively. We concluded that the use of the ConstaVac in the immediate postoperative period is a useful and practical method of autologous transfusion and conservation of a previous resource, and we recommend its use especially in simultaneous bilateral knee arthroplasty.