ObjectiveThe aim of this study was to determine the trends of road traffic injury (RTI) mortality among adolescents aged 10–14 years and 15–19 years across different country income levels with respect to the type of road users from 1990 to 2019.MethodsWe conducted an ecological study. Adolescents’ mortality rates from RTIs at the level of high-income countries (HICs), upper-income to middle-income countries (UMICs), lower-income to middle-income countries and low-income countries were extracted from the Global Burden of Disease study. Time series were plotted to visualise the trends in mortality rates over the years. We also conducted Poisson regression using road traffic mortality rates as the dependent variable and year as the independent variable to model the trend of the change in the annual mean mortality rate, with incidence rate ratios (IRRs) and 95% CIs.ResultsThere were downward mortality trends in all types of road users and income levels among adolescents from 1990 to 2019. HICs had more pronounced reductions in mortality rates than countries of any other income level. For example, the reduction in pedestrians in HICs was IRR 0.94 (95% CI 0.90 to 0.98), while that in UMICs was IRR 0.97 (95% CI 0.95 to 0.99) in adolescents aged 10-14 years.ConclusionsThere are downward trends in RTI mortality in adolescents from 1990 to 2019 globally at all income levels for all types of road users. The decrease in mortality rates is small but a promising finding. However, prevention efforts should be continued as the burden is still high.