Abstract Background Recently an RCT confirmed brace efficacy in adolescent idiopathic scoliosis (AIS) patients. Previously, a Cochrane review suggested also producing studies according to the Scoliosis Research Society (SRS) criteria on the effectiveness of bracing for AIS. Even if the SRS criteria propose a prospective design, until now only one out of 6 published studies was prospective. Our purpose was to evaluate the effects of bracing plus exercises following the SRS and the international Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) criteria for AIS conservative treatment. Methods Study design/setting: prospective cohort study nested in a clinical database of all outpatients of a clinic specialized in scoliosis conservative treatment. Patient sample: seventy-three patients (60 females), age 12 years 10 months ±17 months, 34.4±4.4 Cobb degrees, who satisfied SRS criteria were included out of 3,883 patients at first evaluation. Outcome measures: Cobb angle at the end of treatment according to SRS criteria : (unchanged; worsened 6° or more, over 45° and surgically treated, and rate of improvement of 6° or more). Braces were prescribed for 18–23 hours/day according to curves magnitude and actual international guidelines. Weaning was gradual after Risser 3. All patients performed exercises and were managed according to SOSORT criteria. Results in all patients were analyzed according to intent-to-treat at the end of the treatment. Funding and Conflict of Interest: no. Results Overall 34 patients (52.3%) improved. Seven patients (9.6%) worsened, of which 1 patient progressed beyond 45° and was fused. Referred compliance was assessed during a mean period of 3 years 4 months ±20 months; the median adherence was 99.1% (range 22.2-109.2%). Employing intent-to-treat analysis, there were failures in 11 patients (15.1%). At start, these patients had statistically significant low BMI and kyphosis, high thoracic rotation and higher Cobb angles. Drop-outs showed reduced compliance and years of treatment; their average scoliosis at discontinuation was low: 22.7° (range 16-35°) at Risser 1.3 ± 1. Conclusions Bracing in patients with AIS who satisfy SRS criteria is effective. Combining bracing with exercise according to SOSORT criteria shows better results than the current literature.