Background : Hip replacement arthroplasty is highly traumatic and may be associated with serious perioperative cardir)respiratory and vascular complications. Bone traumatization induces activation of the hemostatic system. A method of assessment of hemostatic function with whole blood is thromboelasto-graphy (TEG), which is a sensitive indicator of platelet interreaction with protein coagulation cascade. The authors investigated the effect of bone cement on blood coagulation during hip arthroplasty by TEG. Methods : Sixty patients scheduled for hip replacement arthroplasty were randomly allocated to either a noncemented group (n = 35) or cemented group (n= 25). All the patients were operated on under general anesthesia. Collected 0.36 ml blood samples were measured by TEG from 210 seconds to 270 seconds after sampling. TEG parameters were measured at preoperation, before and after bone cement insertion (before and after reaming in the noncemented group), at postoperative 6, 24 hours in both grups. Results : There were no significant changes of r, k, a angle, MA and Ly60 irrespective of the use of bone cement. Also, in the cemented group, there were no significant changes in TEG measurements between before and after bone cement insertion. However, there were increase in MA and a angle at postoperative 6 hours compared with preoperation irrespective of the use of bone cement. Conclusions : This study reveals that there are no differences between fixation with and without bone cement in the activation of the cascade systems by hip replacement arthroplasty. (Korean J Anesthesiol 2000; 38: 991 ~ 996)