BACKGROUND: This study sought to assess prevalence rate, comorbidity and predictors of Post-Traumatic Stress Disorder (PTSD), depression and anxiety among adolescents affected by the 2016 Aceh Earthquake. METHODS: A cross-sectional study was conducted six months after the earthquake. The multi-stage random sampling method was applied to a selection of respondents from district schools. A total of 321 students participated in the study. In addition to generating demographic data, a brief PTSD inventory, the Patient Health Questionnaire (PHQ), the Generalized Anxiety Disorder (GAD-7) questionnaire and the Disaster Impact Questionnaire (DIQ) were administered. RESULTS: Approximately 58.3%, 16.8% and 32.1% of adolescents reported the clinical symptoms of PTSD, depression and anxiety, respectively. The associations and comorbidity between PTSD, depression, and anxiety were statistically significant (p = 0.001). Gender, depression, having directly seen someone injured or trapped, the injury or hospitalization of a member of the nuclear family and being afraid to stay inside a building since the earthquake were demonstrated to be the significant predictors for PTSD. The injury and hospitalization of a member of the nuclear family and feeling stressed after the earthquake were significant predictors for depression. Having been injured, having one's house destroyed; being afraid to stay inside a building and gender were significant predictors for generalized anxiety disorder. CONCLUSIONS: The prevalence of PTSD in the current study population is relatively high and the fact that a significant number of adolescents were afraid to stay inside a building following the earthquake calls for further investigation and treatments.