Aim <p>We aimed to estimate the trend, the causes and the economic conditions of neonatal and infant deaths in Poland, and to compare them with the statistics of other European Union (EU) countries.</p> Subject and methods <p>Death records and live births were obtained from the Central Statistical Office of Poland (CSO). Mortality rates (MR) were calculated. The annual percent changes in neonatal and infant MR in 1999–2023 were examined using linear regression. To compare with other European Union countries of MR, Eurostat data was used. The relationship between MR and gross domestic product (GDP) per capita was examined. An ecological study using an analysis of correlation between infant mortality in Poland with chosen economic variables was conducted.</p> Results <p>A significant decrease in neonatal and infant mortality in Poland was noted. However, the MR of extreme immaturity demonstrated a significant increase from 1999 to 2023. The main causes of infant death in Poland were extremely low birth weight, extreme immaturity (&lt; 28&#xa0;weeks of gestation) and congenital malformations. Infant mortality in Poland was still higher than in most EU countries. Significant correlation between the rates of infant deaths and GDP per capita for each country, expressed as a percentage of the EU-27 average, was found. No relationship between infant mortality and selected economic variables, including GDP per capita, in Poland was shown.</p> Conclusion <p>Monitoring the quality of care for newborns with extreme immaturity and extremely low birth weight seems to be an important tool for prevention of infant mortality.</p>