Air pollution, one of ten most important causes of premature mortality worldwide, remains a major issue also in the EU, with more than 400,000 premature deaths due to exposure to PM2.5 reported yearly. The issue is particularly significant in Poland, where there is the highest concentration of PM2.5 among the UE countries. This study focused on the proportion of mortality due to lung cancer and cardiopulmonary diseases attributable to PM2.5 in eleven biggest Polish cities in the years 2006-2011. The findings demonstrate that the mean annual concentration of PM2.5 varied from 14.3 to 52.5 μg/m3. The average population attributable fractions varied from 0.195 to 0.413 in case of lung cancer and from 0.130 to 0.291 for cardiopulmonary diseases. Such substantial values of this ratio translate into a considerable number of deaths, which ranged between 9.6 and 22.8 cases for lung cancer and 48.6 to 136.6 cases for cardiopulmonary diseases per 100,000 inhabitants. We conclude that the impact of PM2.5 concentration on the incidence of premature deaths is unduly high in Polish cities.