INTRODUCTION:
Avoidable mortality serves as a key indicator of health system performance and socioeconomic development. In Brazil, regional disparities persist in socioeconomic and health-system dimensions, potentially stalling progress in reducing deaths amenable to timely medical intervention and public health policies.

METHODS:
We utilized administrative mortality data for 2010/2011 and 2022/2023. We calculated mean yearly avoidable death rates for children under 5 and individuals aged 5–74 (age-standardized) using the Brazilian Ministry of Health’s official classification. Trends were analyzed by cause of death at the municipal, state and national level. Finally, a first-differences regression model identified municipal-level socioeconomic and health-system factors associated with these trends.

RESULTS:
Avoidable mortality fell by 10.3% for children under 5 and 11.9% for the 5–74 age group. While child mortality improved nationwide—most notably in the Northeast and South—progress for the 5–74 group was concentrated in high-income regions, with the North and Northeast showing stagnation. Under-5 trends were primarily driven by improvements in antenatal, delivery, and neonatal care. For those aged 5–34, reductions were linked to external causes, while for those above 35, progress stemmed from reduced mortality due to non-communicable diseases. At the municipal level, expanded access to adequate sanitation was the most consistent predictor of declining mortality across all ages. Increased physician density was significantly associated with mortality reductions only for the 5–74 population. Increased per capita expenditure with health and income transfers were not associated with mortality reductions.

CONCLUSIONS:
While Brazil has reduced avoidable mortality, progress is geographically uneven for adults. Accelerating gains requires prioritizing universal sanitation and the equitable distribution of health professionals at the local level.