This paper presents the result and statistical analysis of the experiment, in which selective anterior or posterior rhizotomy were carried out under microscopic surgery. The materials used for the experiment were 48 young rabbits, and they were divided into four groups. The group I, which was used as control, was subjected to lower dorsal bilateral laminectomies with dural incision, the group II to laminectomies with three right posterior rhizotomies, the group III to laminectomies with three right anterior rhizotomies, and the group IV to laminectomies with three right anterior and posterior rhizotomies. Scoliosis was induced in group Il, Ill and IV. There was no significant statistical difference in the degrees of curvatures among these three groups. The convexity of the curvature faced to the side of the divided roots. In group III and IV, scoliotic curvatures were obvious within two weeks, but there were no considerable changes thereafter. In group Il, the curves progressed slowly up to the 12th week. They were statistically significant at the 4th week and increased continuously thereafter. The histological findings in the group III and IV showed denervation atrophy of the paravertebral muscles at the apex of the curvature, but there was little or no muscle atrophy in the group I and II. We came to a conclusion from the experimental results that scoliosis may be induced not only by anterior root paralysis but also by selective posterior root paralysis