Closed intramedullary nailing for trochanteric fractures of femur has many advantages such as minimal operative trauma, low incidence of infection, good stability of fracture, low incidence of delayed or nounion and early ambulation. Complications have been frequently experienced especially in elderly, osteoporotic patients, but these could be avoided by meticulous surgical procedure. The authors hsve treated 99 cases of intertrochanteric fracture and 23 cases of subtrochanteric fracture from March 1982 to December 1987 with this method and the results are summerized as follows : 1. The aversge age was 61.4 yrs. 2. In classification of intertrochanteric fracture, stable fractures(Kyle type I & II) were 53 cases(43.3%) and unstable fractures(Kyle type III & IV) were 46 cases(37.6%). And in subtrochanteric fracture, stable transverse fractures were 12 cases(9.8%) and unstable long oblique or spiral fractures were 11 cases(9.0%). 3. Intraoperative complications were experienced in 23 cases(18.8%). The entry hole breakage was most common and occurred in 16 cases. 4. Of the 94 patients with more than 6 months follow-up, 21 patients(22.3%) showed more than one complication, e.g, knee joint pain in 15 cases, external rotation deformity in 8 and nail migration in 11 including 3 cases of fixation loss and one case of nonunion with nail breakage, etc. 5. Complications occurred more frequently in unstable fractures(31.8%) and in old ages (29.1%) than in stable fractures and in young ages respectively. And it was felt that complications could be minimized by packing of the medullary canal with nails. 6. It is thought that flexible intramedullary nailing is a good method for trochanteric fractures of femur not only in elderly debilitated patients but also in young patients. However, experience and caution are required to prevent complications.