METHODS This study was designed to investigate the difference of rib length of idiopathic scoliosis using experimentally induced scoliosis by pinealectomy in chickens. OBJECTIVE To find whether the difference of rib length may play a role for the development of scoliosis in pinealectomized chickens. BACKGROUND In experimental and clinical studies, asymmetric growth of the rib has been considered to be one of factors for the development of idiopathic scoliosis. Pinealectomy in chickens consistently produces scoliosis with lordosis, vertebral rotations, and rib humps, which have anatomic characteristics similar to those of human idiopathic scoliosis. METHODS A total of 30 chickens were divided into two groups: pinealectomy in 15 chickens and sham operation in 15 chickens served as control. The surgeries were performed on the second day after hatching. The chickens in both groups were killed at 3 months of age. The spines were examined radiologically for the presence of a scoliotic curve. Also, the ribs at each level were measured and compared between left and right sides. RESULTS All pinealectomized chickens that developed scoliosis showed rib humps. In contrast, none of chickens in a sham operation developed scoliosis. In both groups, there were no significant asymmetries in the rib length. CONCLUSIONS Our results indicated that rib length was not related to the experimental scoliosis examined in this study. Further study is encouraged to investigate if the asymmetric rib length plays a role in causing or promoting other types of scoliosis, especially in primate or human idiopathic scoliosis.