The long-term changes in vital capacity and in total lung capacity after spinal fusion for 43 scoliotic patients are described. The values recorded were seldom lower after surgery but did not show any marked subsequent increases with patient growth. Subsequent increases in volumes are less marked in the group of patients with paralytic scoliosis. These findings suggest that the psychological advantages of improving the patient's appearance by surgery and of preventing any respiratory condition from worsening may be achieved, although the total capacity and vital capacity are not much improved by spinal fusion.