Thirty-one patients with severe adolescent idiopathic scoliosis were evaluated preoperatively by computerized dynamic posturography. Curve type, magnitude and spine balance were measured radiographically. In four girls, a very mild vestibular dysfunction was observed on the sensory organization analysis, and three of them had a horizontal shift of more than 2 cm; a disbalance was observed in only three other patients among the 27 patients with normal posturography. These results suggest that abnormalities in the sensory systems are not involved in the etiology of severe adolescent idiopathic scoliosis. The vestibular dysfunction detected in the four patients was most probably the result of disbalance and not the cause of the disease.