IntroductionAdolescent suicide is a worldwide public health problem, being the second and the third leading cause of death in the 15–29 and the 15–19 age groups, respectively. Among adolescents, it is estimated that for every suicide, there are 100–200 suicide attempts. Although 79% of suicides in the world occur in low/middle-income countries, most of scientific evidence comes from high-income and low-risk countries. In recent years, adolescent suicide rates have steadily increased in Chile. Deaths caused by self-harm increased by 220% in the population aged 10–19 years between 2000 and 2015. The Maule Region is one of the regions of Chile with the highest levels of suicide among those aged 15 and 19 years old. The objective of this study is to evaluate the trajectories of ideation and suicidal attempts in adolescents with psychiatric disorders treated within the public health system of the Maule Region, Chile, based on different clinical, psychological and neuropsychological factors.MethodA prospective naturalistic study of a clinical sample of adolescents under psychiatric treatment in the Maule Region, Chile. Adolescents will be evaluated using a thorough protocol that includes suicide-related clinical variables. The study seeks to establish patterns of change in the trajectories of ideation and suicide attempts among adolescents.Ethics and disseminationEthical approval was granted by the Scientific Ethics Committee of the Universidad Católica del Maule in Chile. This protocol was registered in ClinicalTrials.gov. The results of this study will be disseminated to health centres through executive reports and feedback sessions. In addition, the most relevant findings will be presented in scientific articles, conferences and seminars open to the community.Trial registration numberNCT04635163.