BACKGROUND: Understanding the impact of effective paediatric adherence promotion interventions on patients, families and the healthcare system is necessary to inform efforts to improve healthcare quality and control costs. Building on previous research suggesting that improving adherence may have far-reaching benefits, the objective of this study was to quantify the impact of effective adherence promotion interventions for children and adolescents with a chronic medical condition on patients, families and the healthcare system. METHODS: Authors systematically reviewed articles indexed in PubMed, PsycINFO and CINAHL to identify randomized controlled trials of paediatric adherence promotion interventions. Interventions that improved paediatric adherence and examined patient-level, family-level or healthcare system-level outcomes in children and adolescents (M age