A clinical and radiologic follow-up study of a group of 75 children and adolescents, comprised of both boys and girls, who underwent spondylodesis for spondylolisthesis between the years 1979 and 1984 is reported. Sagittal rotation, lumbosacral joint angle, lumbar lordosis, wedging of olisthetic vertebrae, and the rounding of the upper sacrum showed considerable statistical correlation to the amount of slipping and accordingly should be noted when estimating the risk of progression of the spondylolisthesis. When the spondylolisthesis was accompanied by scoliosis, it was noted that seriousness of the former was closely correlated to that of the latter. Most patients profited by the operation, and solid fusion was achieved in almost all cases. The posterolateral spondylolysis performed using graft from the iliac crest, the interbody fusion technique, or their combination turned out to be the most reliable surgical methods. The combined technique was especially required in cases with a high degree of slipping.