To assess the sagittal orientation of the cervical and thoracolumbar spine, 38 adolescents with idiopathic scoliosis were studied. The C7 plumb line and Cobb angles from C2-6, T1-12, and L1-S1 were measured on preoperative films. Lateral radiographs with > 1-year follow-up after surgical correction were available for the same measurements in 28 patients. The preoperative curve from C2-6 was 6 +/- 11 degrees of kyphosis. There was a significant correlation between the loss of thoracic kyphosis and the development of cervical kyphosis for the entire group preoperatively (p = 0.009). Postoperatively, cervical kyphosis increased to 11 +/- 9 degrees at 1-year follow-up (p = 0.05). There was no progression of cervical kyphosis in patients with "thoracic hypokyphosis" (kyphosis < 20 degrees). Cervical kyphosis increased in patients with "normal" thoracic kyphosis (20-40 degrees) and in patients with hyperkyphosis (kyphosis > 40 degrees) after surgery, despite preservation of thoracolumbar sagittal contour. There were no significant differences between the sagittal contour of patients treated with Cotrel-Dubousset or Harrington instrumentation.