Pinealectomy in young chickens consistently results in scoliosis which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the aetiology of AIS and can lead to the development of novel treatement methods.