Objective. To determine the expression level of the genes encoding the paraoxonase family enzymes (PON1, PON2, and PON3) in the placentas of women with uncomplicated pregnancy and in the development of preeclampsia Materials and methods. The investigation enrolled 26 pregnant women aged 24 to 35 years, including 14 women with normal pregnancy and 12 with preeclampsia. The expression of the PON1, PON2, and PON3 genes was analyzed by real-time PCR using the primers specific to these genes. Results. Women whose pregnancy was complicated by preeclampsia showed a significant decrease in the placental expression of the PON2 gene. The lowest PON2 gene expression was found in the placentas of women with severe preeclampsia. There were no significant differences in the placental expression level of the PON1 and PON3 genes in women with preeclampsia compared to healthy women. Conclusion. In women with preeclampsia, the placental PON2 gene expression decreases; however, the expression level of the PON1 and PON3 genes does not differ from that of the PON1 and PON3 genes in the placentas of patients with physiological pregnancy. The placental expression of the PON2 gene depends on the severity of preeclampsia; is lower in severe preeclampsia than in moderate preeclampsia. © Bionika Media Ltd.