PURPOSE: The purpose of this study is to investigate the effectiveness of trochanter stabilizing plate (TSP) with compression hip screw(CHS) on the reduction stability, fracture union and sliding of lag screw in unstable intertrochanteric fracture. MATERIAL AND METHOD: From October 1997 to March 1999, 32 cases(group 1) and 20 cases(group 2) who could be followed for more than 1 year were treated with TSP (group 2) and CHS only (group 1) due to unstable intertrochanteric fractures. And two groups were compared clinically and radiologically. RESULTS: Operation time was longer in group 2 and hospital stay was longer in group 1. Preoperative functions were better in group 1(7.00 points) than in group 2(6.47 points). When postop. function was compared with preop. function, group 1 showed differences on the three months follow-up and six months follow-up. Whereas group 2 only showed difference on the three months follow-up but not on the six months follow-up. There was no difference in the incidence of lag screw sliding. However, there were differences in the extent of sliding between group 1(ave.4.88mm) and group 2(ave.2.88mm) with three months follow-up and six months follow-up (group 1: ave 5.42mm and group 2: ave. 3.03mm). There was a significant difference between group 1(12cases) and group 2(0 case) in greater trochanter lateralization, but shaft medialization between group 1(17cases) and group 2(10cases) showed no difference. Loss of neck-shaft angles between group 1(9cases) and group 2(3cases) were not significantly different. Due to loss of reduction, one case in group 1 was reoperated. CONCLUSION: Application of TSP is not a difficult procedure and reduce excessive sliding of lag screw. And early fuctional recovery without adverse effect of bone healing is possible. So in unstable intertrochanteric fracture, additional use of TSP is effective.