BACKGROUND: To study the impact of oxidative damage associated with particulate matter< 2.5 µm (PM2.5) during prenatal period on the cognitive development in five years old children. METHODS: Two cohorts of children aged five years, born in the years 2013 and 2014, were studied for their cognitive development in the polluted district Karvina and the control district Ceske Budejovice. Exposure to PM2.5 in the ambient air was measured for each mother during the 3rd trimester of pregnancy. Oxidative damage was determined from the level of biomarkers at delivery in mothers´ and newborns´ urine as 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG) and in plasma as 15-F2t-isoprostane levels (15-F2t-IsoP). The Bender Visual Motor Gestalt Test (BG test) and the Raven Colored Progressive Matrices (RCPM test) were used as psychological cognitive tests. RESULTS: Average concentrations of PM2.5 ± SD in the 3rd trimester of mothers´ pregnancies were 37.7 ± 14.7 µg/m3 and 17.1 ± 4.8 µg/m3 in Karvina and Ceske Budejovice, respectively (p < 0.001). The maternal level of 15-F2t-IsoP in plasma at the time of delivery was significantly associated with the results of the RCPM test (p < 0.05) and the BG test (p < 0.05) in five years old children. CONCLUSIONS: Lipid peroxidation in maternal plasma at the time of delivery has an adverse effect on the results of psychological cognitive tests in five years old children.