We retrospectively reviewed the magnetic resonance imaging studies that had been made for ninety-five patients who had idiopathic scoliosis. We wished to determine if we could identify any criteria that should be met before these studies are performed. The study group included thirty-one male patients and sixty-four female patients. The average age at the time of the imaging study was thirteen years (range, one to twenty-eight years). The average curve was 41 degrees (range, 11 to 95 degrees). Fourteen patients were seen to have an intraspinal abnormality on the imaging study: twelve had a syrinx, one had a syrinx and an astrocytoma of the spinal cord, and one had dural ectasia. Five of the eight patients who were less than eleven years old and who had a left thoracic curve had an intraspinal abnormality on the imaging study, but this combination of factors did not indicate the need for operative intervention. Four of the intraspinal abnormalities in the fourteen patients necessitated neurosurgical intervention; if the criteria for obtaining the imaging study had been restricted to neck pain and headache--particularly with exertion--and neurological findings such as ataxia, weakness, and a cavus foot, these abnormalities would have been diagnosed.