A retrospective study was made of 37 patients with 54 fractures that occurred without significant trauma. The morbidity and causes of these pathological fractures in patients with cerebral palsy were analyzed. The major causes for the fractures were long and fragile lever arms and stiffness in major joints, particularly the hips and knees. An additional factor was severe osteoporosis following a long period of postoperative immobilization. Seventy-four percent of the fractures occurred in the femoral shaft and supracondylar region. Stress fractures were rare (7%) and involved only the patella. Conservative treatment was sufficient in most cases but surgical fixation provided a good alternative for fractures of the femoral shaft. Intraarticular fractures with joint incongruity resulted in a decreased level of activity of the patient. Since osteoporosis is a major risk factor, patients with cerebral palsy should bear weight to prevent pathological fractures. Any stiffness of major joints and extended periods of immobilization should be avoided.