The authors analyzed the clinical and imaging findings in 30 consecutive pediatric, adolescent, and young adult patients who underwent MR imaging because of atypical features of idiopathic scoliosis. Atypical clinical and plain radiographic features included early onset (n = 4), rapid progression (n = 19), pain (n = 17), other neurologic symptoms or signs (n = 12), associated syndromes (n = 4), a convex left thoracic or thoracolumbar curve (n = 18), a kyphotic component (n = 7), and pedicle thinning (n = 4). MR imaging demonstrated 17 abnormalities in 11 patients: lumbar disk protrusions (n = 1), patulous intradural space (dural ectasia) (n = 3), hydrosyringomyelia (n = 7), Chiari I malformation (n = 5), and cord astrocytoma (n = 1). Significant associations with abnormal MR imaging findings were shown for patients with pain, weakness, abnormal neurologic findings, and atypical curvatures. Furthermore, there was a striking association of convex left thoracic or thoracolumbar scoliosis with hydrosyringomyelia (six of seven cases). On the basis of these results, "atypical" spinal curvatures at radiography and "atypical" clinical features should prompt performance of additional diagnostic studies.