Idiopathic scoliosis is a complex deformity that deviates the trunk from its normal plane of symmetry and induces geometric changes of the spine in the three dimensions of space. The natural course of idiopathic scoliosis can be influenced by Cheneau-brace treatment.Brace treatment is based on a three point principle. We measured the Harrington prognostic index after one year of conservative treatment. We followed 33 patients for one year, we asked for spinal radiography in orthostatic and in brace. We detected changes of the measured Cobb angle before and after treatment. Those who had the prognostic index less than 5, (considered a good prognosis), after one year of treatment had a correction index (Harrington) 47.5%. In cases when the prognostic index was more than 5, after treatment the correction index was 25.3%. In cases when the Cobb-angle was less than 30 degrees we had the best correction index: 49.3%. We assumed that it is very important to treat the scoliosis in time, when the correction can be the most significant.