A retrospective study was conducted in 122 patients with idiopathic scoliosis who were followed for more than 2 years. There were 58 patients who showed 5° (Cobb) or more progression, and 41 patients who showed no progression. Only those who did not receive any treatment or who failed to comply with brace treatment were selected, to eliminate the effect of treatment. In the early phase of the study, 12 parameters were put into a multivariate analysis to observe the relative weight of each of them, which led the authors to eliminate the following five parameters: 1) Cobb angle, 2) rotation of the apical vertebra, 3) deviation of the apical vertebra, 4) Risser's expected correction: (standing angle - supine angle) X 3, and 5) maturation index of the Iliac apophysis. Through a multiple regression analysis, an equation was obtained to correlate the predictive and the real progression within 10° deviation.