The purpose of this study was to determine the incidence of intraspinal pathology presenting as idiopathic scoliosis in children less than 11 years of age and otherwise neurologically normal. Twenty-six consecutive patients (5 boys, 21 girls) with idiopathic scoliosis measuring at least 15 degrees were studied with magnetic resonance imaging. Five children (19.2%) were diagnosed by magnetic resonance imaging to have Chiari-I malformations with hydromyelia (two patients), syringomelia (one patient), intramedullary tumor (one patient) and terminal lipoma (one patient). Only two of the five patients had left thoracic curves. Intramedullary spinal cord pathology can present as scoliosis without neurologic signs. Scoliosis can be the initial neurologic sign suggesting intraspinal pathology, and magnetic resonance imaging is indicated in routine evaluation of children less than 11 years of age.