A computer network system connecting the operating rooms and the blood transfusion service to control blood ordering and provision was implemented in March 2007 in an attempt to ensure the appropriate cross-checking of blood products and the registration of blood product usage. This system connected the blood control system of the blood transfusion service with the anesthetic system of the operating room and the hospital general medical system. Using this system, the patient’s wrist band is checked upon admission to the operating room, and anesthetists request the provision of blood products, order new blood products, cross-check the provided products, register their use, and record the occurrence of adverse events. On the blood transfusion service side, the blood products to be provided are cross-checked against the anesthetists’ request, the results of the cross-match test are checked, and the attachment of the appropriate matching confirmation label to the blood product is confirmed using the system. The anesthetists and the blood transfusion service staff can check the real-time list of the blood products available for the surgical patient and those already transfused. Thus, following implementation of this system, the excessive ordering of blood products by anesthetists could be avoided, the appropriate registry of the cross-checking of blood products against the patient would become available, and medical errors could be avoided. At the time of its implementation, however, incidents occurred as a result of the lack of experience of various professionals, including anesthetists, nurses, and medical technologists, who needed extensive training to be fully able to navigate this system, which works 24 h a day, including holidays. Hence, we intend to expand its function, especially to improve the prevention of medical errors.