Infant deaths were classified as avoidable, non-avoidable, and resulting from ill-defined conditions, from 1997 to 2006, using the Brazilian List of Avoidable Causes of Mortality. Non-linear regression was used to calculate trends in cause-specific infant mortality rates. There was a significant decline in both avoidable deaths and deaths from ill-defined causes (p < 0.001). Avoidable deaths decreased by 37% overall. Mortality avoidable through adequate intrapartum care and adequate neonatal care decreased by 27.7% and 42.5%, respectively, while mortality avoidable through adequate prenatal care increased by 28.3%. In conclusion, health services contributed to the reduction in infant mortality. The decrease in ill-defined causes of death indicates expanded access to health services. The increase in access to intrapartum and neonatal care contributed to the reduction in infant deaths. The increase in mortality avoidable through adequate prenatal care indicates the need for improvement in prenatal care.