Background: Health risk behaviours during adolescence can have long-term negative consequences. Little is known, however, about the recent health risk behaviour trends in adolescents in Lebanon, This investigation aimed to report the trends in the prevalence of various health risk behaviours, such as alcohol use, dietary behaviour, interpersonal violence, mental health, oral and hand hygiene, among adolescents in Lebanon.Methods: Cross-sectional nationally representative data were analysed from 13,109 adolescents (14 years median age) that participated in three waves (2005, 2011 and 2017) of the “Lebanon Global School-Based Student Health Survey (GSHS)”.Results: Significant improvements were found among both boys and girls in the decline of interpersonal violence (bulling victimization, being physically attack and involvement in physical fighting), poor washing of hands after using the toilet, and suicide plan, and among girls only loneliness, worry-induced sleep disturbance and suicidal ideation. Significant increases were found among both boys and girls in the prevalence of inadequate fruit consumption, and among boys only unintentional injury and not always washing hands before eating.Conclusion: Several decreases but also increases of health risk behaviours were found over three assessment points during a period of 12 years calling for continued health enhancing activities in this adolescent population.