This study reports the comparison of the clinical use of a new tourniquet system for total knee arthroplasty that can determine its pressure in synchrony with systolic blood pressure (SBP) with the conventional that keeps the initial setting pressure. We prospectively applied the additional pressure of 100 mmHg based on the SBP recorded prior to skin incision to consecutive 72 procedures (conventional; initial 36, new; following 36). Six knees with the conventional and none of 5 with the new showed oozing blood in surgical field after sharp rise in SBP. According to statistically no difference of the perioperative blood loss without any tourniquet-related postoperative complications in both groups, the new system seemed to be much practical device especially for controlling a bloodless surgical field.