Background: Mortality-to-incidence ratio (MIR) is a pragmatic population-level indicator of cancer survival and health system performance. In pediatric leukemia, age-specific MIR variation may reflect differences in treatment response, disease biology , access to pediatricintensive care (PICU), and complication-related mortality . We evaluated age-stratified MIR patterns to identify vulnerable subgroups and implications for pediatric critical care delivery in a middle-income setting. Methods: National registry data for pediatric leukemia (0–19 years) were analyzed, including age-specific incidence and mortality counts. Age groups were categorized as 0–4, 5–9, 10–14, and 15–19 years. MIR was calculated for each age group as mortality divided by incidence.Descriptive comparisons were performed across developmental strata, and patterns were interpreted in relation to known subtype distribution and adolescent disease burden. Results: A total of 2,829 incident pediatric leukemia cases were identified, with the highest incidence observed in children aged 0–4 years (39.0%). Age-stratified MIR demonstrated heterogeneity across developmental stages. MIR was relatively lower in mid-childhood (5–9 years) and comparatively higher in adolescents (15–19 years). The adolescent group, characterized by a higher proportion of acute myeloid leukemia, showed increased mortality burden relative to incidence, suggesting greater clinical complexity and intensive care vulnerability . Conclusions: Age-stratified MIR reveals developmental disparities in pediatric leukemia outcomes within a middle-income setting. Elevated MIR in adolescents highlights the need for strengthened PICU capacity , early sepsis management, and age-adapted supportive care strategies. MIR-based surveillance may serve as a simple tool for monitoring pediatric oncology system performance.