Introduction: Adolescent self-injury and suicidality represent significant public health challenges, often rooted to life stressors. Although Adverse Childhood Experiences (ACEs) are known precursors for self-injury and suicidality , data among Sri Lankan adolescents are limited. Objectives: To determine the incidence of self-harm and suicidality (suicidal ideation and suicidal attempt) and to describe their associations with ACEs, risk behaviours and mental health issues among 16-17-year-old school-going adolescents in Vavuniya district, Sri Lanka. Methods: A cross-sectional study was conducted among adolescents in Vavuniya district, Sri Lanka, using a pre-tested selfadministered questionnaire. ACEs questions were adapted from 17-item Paediatric ACEs Screening and Related Life-events Screener. Ethical approval was obtained, and the data were analysed using SPSS. Results: A total of 461 adolescents were recruited, of whom 57% had experienced at least one ACE. The incidence of selfharm and suicidality during the past year was reported as 14.1% for self-injury , 11.1% for suicidal ideation, and 5.9% for suicidal attempts. ACEs were significantly associated with increased risks for self-injury and suicidality (p