The purpose of this study was to determine the effectiveness of Texas Scottish Rite Hospital (TSRH) Instru-merıtation a recently developed system, in the treatment of late onset idiopathic scoliosis. From September 1991 to December 1993, 53 patients treated with TSRH for idiopathic scoliosis in the 1st and 2nd Department of Ortho-paedics and Traumatology of Ankara Social Security Hospital were examined retrospectively. When ali curve types were included, the mean preoperative Cobb angle of the majör curve that was 59.8+15.6 vvas corrected by 58.8+19.9%. The highest correction rate was obtained in King Type III curves with a single thoracic flexible curve (mean 64.4%). İn 67.9% of the patients physiologic thoracal kyphosis and in 43.4% physiologic lumbar lordosis was reconstitued. Ali patients had an improvement in pulmonary functions at 6 months follow-up. These results suggested that TSRH system is a one of the best choices in the surgical treatment of idiopathic scoliosis, as it has advantages such as providing high correction rates of the deformity and possibility of building a more rigid frame with cross-link plates.