There have been several reports of experimental studies on scoliosis induced by posterior rhizotomy, but no reports of experiments designed to induce scoliosis by partial posterior rhizoto-my. This study was done to investigate the effect of partial and total posterior rhizotomy on the induction of scoliosis. In this experiment, 75 young rabbits divided into 5 groups were used. A lamminecytomy with an opening of the dura mater was performed between the 7th and the 10th thoracic vertebral levels on all the rabbits. The rabbits in Group I served as the control, and no additional operation was done. In Group II, a unilateral transection of one posterior root was done. In Group III, a unilateral transection of one posterior root was done. In Group IV, a unilateral partial transection of one posterior root was done. In Group V, a unilateral partial transection of three successive posterior roots was done. Statistically significant scoliosis was induced only in Group III where three posterior roots had been transected. Induced scoliotic curvatures were directed to the side of the rhizotomies. Statistically significant scoliosis was not induced in the oterh groups. Histological preparation of the spinal cord showed marked demyelinization in the posterior and posterolat eral column of the white matter in Group II and Group III where a total transection of the posterior root had been done. But there was much less demyelinization in Group IV and Group V where a partial transection of the posterior root had been done. In this experimental study, scoliosis was preduced by transection of three posterior roots but not by transection of one posterior root or by partial transection of one or three posterior roots.