ABSTRACT: BACKGROUND:In the World Health Organization Western Pacific Region (WHO WPRO), most adolescents enroll in secondary school. Safe, healthy and nurturing school environments are critical for adolescent health and development. Yet, there were no systematic reviews found on the efficacy of school-based interventions among adolescents living in low and middle income countries (LMIC) in the Region. There is an urgent need to identify effective school-based interventions and facilitating factors for successful implementation in adolescent health in WPRO. METHODS:For this systematic review, we used five electronic databases to search for school-based interventions to promote adolescent health published from January 1995 to March 2019. We searched RCT and non-RCT studies among adolescents between 10 to 19 years old, done in LMIC of WHO WPRO, and targeted health and behaviour, school environment and academic outcomes. Quality of studies, risk of bias and treatment effects were analyzed. Effective interventions and implementation approaches were summarized for consideration in scale-up. RESULTS:Despite a broad key term search strategy, we identified only eight publications (with 18,774 participants). Most of the studies used knowledge, attitudes and behaviours as outcome measures. A few also included changes in the school policy and physical environment as outcome measures while only one used BMI, waist circumference and quality of life as their outcome measures. The topics in these studies included: AIDS, sexual and reproductive health, de-worming, nutrition, obesity, tobacco use, and suicide. Some interventions were reported to be successful in improving knowledge, attitudes and behaviours, but their impact and scale were limited. The interventions used by the different studies varied from those that addressed a single action area (e.g. developing personal skills) or a combination of action areas in health promotion, e.g. developing a health policy, creating a supportive environment and developing personal skills. No intervention study was found on other important issues such as screening, counseling and developing safe and nurturing school environments. CONCLUSIONS:Only eight school-based health interventions were conducted in the Region. This study found that school-based interventions were effective in changing knowledge, attitudes, behaviors, healthy policies and environment. Moreover, it was clarified that policy support, involving multiple stakeholders, incorporating existing curriculum, student participation as crucial factors for successful implementation.