During the orthopedic surgical procedures, replacement of a substantial amount of lost blood is necessary frequently. Various homologous blood transfusion reactions such as, allergic reaction, febrile reaction, immunologic reaction and transmission of viral agents were well known. For the purpose of reducing these side reactions, we performed prebanked autologous transfusion at St. Vincent Hospital, and analyzed the amount of transfused blood, pre and post operative hemoglobin level between 40 patients who had prebanked autologus transfustion from September 1989 to May 1990 and 42 patients who had homologous transfusion from July 1988 to August 1989. The results were as follows:1. The cases of prebanked autologous transfusion were 15 in spine fusion, 17 in joint replacement and 8 in other surgery. The cases of homologous transfusion were 22 in spine fusion, 20 in joint replacement surgery. 2. In homologous transfusion group, the mean requirements for transfustion were 2.7 units in spine fusion and 2.1 units in joint replacement surgery, similarly in autologous transfusion group, the mean requirements for transfusion (including homologous and autologous blood) were 3.0 units in spine fusion, 1.7 units in joint replacement. 3. The mean amount,s of prebanked autologous blood transfusion were 1.9 units in spine fusion and 1.2 units in joint replacement surgery. The amounts of prebanked autologous blood transfusion were 66.2% of total blood transfusion. In 15 patients (38%) among 40 autologous transfusion group, prebanked autologous blood only was required for transfusion. 4. The level of hemoglobin averaged 11.9g/dl at the time of immediate after operation in prebanked group, but 13.4g/dl in homologous transfusion group. The level of hemoglobin averaged 11.2g/dl at the time of postoperative period in prebanked group and 11.7g/dl in homologous transfusion group. The prebanked autologous transfusion in the orthopedic operations reduced needs for homologous blood transfusion. It was thought to be effective method to prevent the risk of the various transfusion reactions during operation.