One hundred independently mobile patients over the age of 75 who had an unstable intertrochanteric or subtrochanteric fracture were treated with primary prosthetic replacement. In all patients a cemented femoral component with diaphyseal support was used. A bipolar arthroplasty was performed in 91 patients and a total hip arthroplasty in 9 patients because of associated coxarthrosis. The functional results according to the Merle d'Aubigné hip rating scale were excellent, very good or good in 78% of the hips. The dislocation rate of 44.5% in the patient group who underwent total hip arthroplasty was significantly higher than the 3.3% in those who had bipolar arthroplasty. Associated with the dislocations was a much higher incidence of pressure sores and pulmonary complications. Adverse effects on the femoral side included 4 cases with progressive loosening of the screws used to fix the greater trochanter to the femoral component, 1 fracture of the distal femur and 1 pseudarthrosis of the bone envelope surrounding the femoral component.