Objectives: To describe the prevalence of gambling disorders in adolescent students in Ontario. Method: Data were based on a random survey of 2371 Ontario students in grades 7 to 13 using the South Oaks Gambling Screen revised for adolescents (SOGS-RA). Results: In total, 5.8% of students met the criteria for past-year problem gambling, and an additional 7.5% met the criteria for at-risk gambling. Gambling disorders were significantly higher among male students than female, but did not differ significantly by age or region. Conclusion: The prevalence of gambling disorders among adolescents warrants thorough investigation and ongoing monitoring.