BACKGROUND: Finding an optimal treatment strategy for adolescent idiopathic scoliosis (AIS) patients remains challenging because of its intrinsic complexity. For mild to moderate scoliosis patients with lower skeletal growth potential (Risser 3-5), most clinicians agree with observation treatment; however, the curve progression that occurs during puberty, the adolescent period, and even in adulthood, remains a challenging issue for clinicians. The aim of the study is to investigate the efficacy of Schroth exercise in AIS patients with lower skeletal growth potential (Risser 3-5) and moderate scoliosis (Cobb angle 20°-40°). METHODS: From 2015 to 2017, data of 64 patients diagnosed with AIS in Peking University Third Hospital were reviewed. Forty-three patients underwent Schroth exercise were classified as Schroth group, and 21 patients underwent observation were classified as observation group. Outcomes were measured by health-related quality of life (HRQOL) and radiographic parameters. HRQOL was assessed using the visual analog scale (VAS) scores for back, Scoliosis Research Society-22 (SRS-22) patient questionnaire. Radiographic spinopelvic parameters were obtained from anteroposterior and lateral X-rays. The pre-treatment and post-treatment HRQOL and radiographic parameters were tested to validate Schroth exercise efficacy. The inter-rater reliability of the radiographic parameters was tested using the interclass correlation coefficient (ICC). The paired t test was used to examine HRQOL and radiographic parameters. Clinical relevance between C2-C7 sagittal vertical axis (SVA) and thoracic kyphosis was analyzed using Spearman correlation. RESULTS: In Schroth group, VAS back score, SRS-22 pain, and SRS-22 self-image domain were significantly improved from pre-treatment 3.0 ± 0.8, 3.6 ± 0.5, and 3.5 ± 0.7 to post-treatment 1.6 ± 0.6 (t = 5.578, P = 0.013), 4.0 ± 0.3 (t = -3.918, P = 0.001), and 3.7 ± 0.4 (t = -6.468, P < 0.001), respectively. No significant improvements of SRS-22 function domain (t = -2.825, P = 0.088) and mental health domain (t = -3.174, P = 0.061) were observed. The mean Cobb angle decreased from 28.9 ± 5.5° to 26.3 ± 5.2° at the final follow-up, despite no statistical significance was observed (t = 1.853, P = 0.102). The mean C2-C7 SVA value decreased from 21.7 ± 8.4 mm to 17.0 ± 8.0 mm (t = -1.224 P = 0.049) and mean T1 tilt decreased from 4.9 ± 4.2 ° to 3.5 ± 3.1° (t = 2.913, P = 0.011). No significant improvement of radiographic parameters and HRQOL were observed in observation group. CONCLUSIONS: For AIS patients with a Risser 3-5 and a Cobb angle 20°-40°, Schroth exercises improved HRQOL and halted curve progression during the follow-up period. Both cervical spine alignment and shoulder balance were also significantly improved after Schroth exercises. We recommend Schroth exercises for patients with AIS.