A fifty five-year-old man who had been decrease in levels of coagulation factors V, VIII, X and XI was monitored by thromboelastography(TEG) to evaluate the effectiveness of blood component replacement therapy during operation of chest wall reconstruction. Cryoprecipitate(9 units) was infused in the preoperative day because the clot formation rate was slow( : 27.5 ). During the operation cryoprecipitate(9 units), fresh frozen plasma(9 units), whole blood(2 units) and packed red blood cells(6 units) were transfused for blood loss of 4000 ml and abnormal findings on TEG. The operation site was not abnormal bleeding tendency. So TEG patterns were normal toward the end of operation. As a result, TEG is effective to monitor hemostasis and guide for transfusion therapy of coagulation abnormalities associated with intraoperative blood loss.