Placental oxidative stress was suggested to play a role in the pathogenesis of pre-eclampsia (PE). In this study, levels of 8-hydroxy-2"-deoxyguanosine (8-OH-dG), a well-established marker of oxidative DNA damage, were analysed in placental cellular DNA from normal (group NP) and pre-eclamptic (group PE) pregnancies as well as from PE pregnancies complicated by intrauterine growth restriction (group PE-IUGR). Placental samples obtained immediately after delivery were frozen at -80 degrees C until analysis. Cellular DNA was isolated, hydrolysed and analysed using high-performance liquid chromatography. Native nucleosides were monitored at 254 nm and 8-OH-dG using electrochemical detection. Concentrations of 8-OH-dG were expressed as micro mol/mol 2"-deoxyguanosine. In group NP, mean concentration of 8-OH-dG reached 179.97+/-80.58 (+/-SEM; micro mol/mol dG). 8-OH-dG levels were higher in group PE (273.44+/-110.14 micro mol/mol), but the difference was not significant in comparison with group NP. Highest concentrations of 8-OH-dG were found in group PE-IUGR (428.97+/-141.40 micro mol/mol), with levels significantly higher than in group NP, but not group PE. The results indicate a positive correlation between the severity of PE and the degree of oxidative stress and corroborate previous studies suggesting reactive oxygen species to be involved in the pathophysiology of PE.