Between 1969 and 1989, we performed posterior segmental instrumentation on 38 patients with thoracic Scheuermann's kyphosis. We used a dynamic system without sublaminar fixation, and a kyphosis of 50 degrees was the main indication for surgery. The mean initial angle was 68 degrees (50 to 100) and the mean final kyphosis was 43 degrees at five-year follow-up, with a mean final loss after surgery of 3.7 degrees. Reconstruction of the vertebral bodies, vertebral wedging and the anterior-body height ratio were observed even in skeletally mature patients. There were no medical complications. There were three cases of loss of correction by more than 10 degrees and one of rod fracture with pseudarthrosis. The role of non-operative treatment is evaluated and early surgical treatment is advocated.