We reviewed the clinical charts and spinal radiographs of fifty-one boys who had Duchenne muscular dystrophy, had not had surgical treatment of the spine, and had been followed until death. All had scoliosis. None of the following variables was useful in predicting which curves would become severe: age when the patient initially walked, age when he ceased walking, age at onset of spinal collapse, surgical release of the iliotibial bands, or age at the time of death. Radiographs were made within eighteen months before death for thirty-three patients; in thirty-one of them, the final curve exceeded 40 degrees and in seventeen, 90 degrees. For the remaining eighteen patients, final radiographs were made more than eighteen months before death; at that time, eight of them already had a curve of more than 90 degrees. Although there was a relationship between extension of the lumbar spine and severity of scoliosis at the time of final follow-up, early maintenance of the lumbar spine in extension rarely prevented the development of a severe curve. For most of the patients who had a severe curve, sitting was difficult and was accompanied by breakdown of the skin and pain. When a patient's curve exceeded 35 degrees, the vital capacity usually was less than 40 per cent of the predicted normal value. Therefore, when walking becomes impossible for boys who have Duchenne muscular dystrophy, routine spinal arthrodesis should be considered.