The risk of progression of idiopathic scoliosis is correlated primarily to factors that predict potential remaining skeletal growth. The aim of the current study was to evaluate spinal growth, measured as the length of the scoliotic spine on serial longitudinal radiographs, and its relationship to progression of the scoliotic curve. The retrospective study was based on measurements made on standing anteroposterior radiographs of 60 patients with adolescent idiopathic scoliosis. In all patients, a Boston brace was prescribed during the followup period. Despite brace treatment, a significantly greater average progression rate of the scoliotic curve was seen in periods of rapid to moderate growth (≥ 10 mm per year) compared with periods of small or no growth (< 10 mm per year). The difference in progression rates concerned the increase of the Cobb angle and the increase of lateral deviation and axial rotation. These findings indicate the length of the spine measured on subsequent radiographs is an excellent parameter to determine spinal growth and thus an excellent predictor of scoliosis progression. With the presented growth charts, which were derived from the measured individual growth velocity values of the patients in the study, it is possible to predict future spinal growth at different chronologic ages.