The results of pulmonary-function studies done on sixty-three patients with paralytic and non-paralytic scoliosis are presented. The results confirm the concept that angular deformities of the spine cause impairment of pulmonary function. The results also demonstrate that the application of the preoperative corrective device further reduces pulmonary function except when the halo apparatus is used as the corrective device. There is no significant improvement of pulmonary function following spine fusion. The importance of blood-gas and diffusion-capacity studies is discussed.