© 2015 Elsevier Inc. All rights reserved. Background context: The value of scoliosis screening has been recently shown in a multicenter randomized controlled trial. However, the long-term sustainability of the clinical effectiveness of scoliosis screening as a routine health service remains unknown. Purpose: The aim of this study was to assess the sustainability of the clinical effectiveness of school scoliosis screening. Study design/setting: A large population-based cohort study with a 10-year follow-up was conducted. Patient sample: A total of 394,401 students who were in the fifth grade during the five academic years from 1995/1996 to 1999/2000 formed five consecutive annual cohorts. The students were eligible for the Hong Kong scoliosis screening program, with their screening history and medical records until their nineteenth birthdays being assessed. Outcome measures: The outcome measures considered in the study were development of adolescent idiopathic scoliosis by the 19 years of age and the Cobb angle. Methods: The clinical effectiveness of scoliosis screening was assessed by referral rate for radiographic diagnosis, sensitivity, specificity, and predictive values. Results: A total of 306,144 students (78%) participated in scoliosis screening, which used a two-tier system. The prevalence of curves of 20 or greater was 1.8% (95% confidence interval [CI], 1.7-1.8%), whereas the referral rate for radiography, the sensitivity, and the positive predictive value (PPV) for curves of 20 or greater were 4.1% (95% CI, 4.0-4.2%), 91% (95% CI, 90-92%), and 40% (95% CI, 39-41%), respectively. Across the five consecutive annual cohorts, the prevalence and sensitivity for curves of 20 or greater increased by 0.23% (95% CI, 0.21-0.25%; p