Background: Youth is undeniably the most important force and resource of any country, thus, identifying the leading causes of death among them to develop preventable interventions is essential. This study aimed to determine the trend of mortality rate and the leading cause of death, based on the ICD-10, among young people in Iran.Methods: The present study is a retrospective cohort and examines the trend of Iranian youth mortality, aged 15-24 years, between 1990 and 2017. The data source was the Global Burden of Disease (GBD) website. Linear Regression analysis was used to measure the slope of changes in mortality rates and causes of mortality during the period, where "time" was the independent variable and "mortality rate" and "causes of mortality" were dependent variables.Results: the death rate of young people declined by 54% during the period, equal to an average of 1.37 units per year. The most common cause of death has been injuries (70%), and then NCDs (25%) and finally communicable diseases (5%). However, death due to injuries (except SUD) and communicable diseases (except HIV) declined significantly by 0.94 and 0.09 units per year, respectively (P<0.001), while, death due to the NCDs had an increasing trend by 0.12 units per year over 28 years (P=0.006).Conclusion: Examining past trends in death rates and causes strengthens insights into the state and future trends in health and death-related indicators, which are crucial for policy-making, especially in developing countries with limited resources.