There are many problems in treatment of intertrochanteric fractures due to osteoporosis and unstable pattern of fractures in old ages and they are different from those in young ages, for example, type of fracture, degree of osteoporosis, and general condition, ect. Anthors studied about the prognostic factors of 42 cases among 88 patients with intertrochanteric fractures, who were treated and followed up from Jan. 1982 to Dec. 1987. 1. The patients under 50 years old were mainly males(94.4%) and its chief cause of injury was traffic accident or fall down(72.2%). The cause of injury over 50 years old was slip down on ground(62.9%). 2. The osteoporosis was increased according to increased age of patients and then the unstable type of fracture was increased. In yaung patients, the unstable intertrochanteric fracture was rare despite of high violent injury. 3. The bone union of the follow-up patients was gained at average 13.8 weeks. 4. The sliding degree of lag screw was increased with unstable fracture and the incidence of metal protrusion into joint cavity was increased in the patients of eccentric fixation of lag screw into femoral head. 5. The all cases of complication were occured in osteoporotic patients over 50 years old and their causes were inadequate fixation of unstable fracture. 6. The most important factors in prognosis of intertrochanteric fractures are initial pattern of fractures, degree of osteoporosis and adequacy of reduction state(postop.).