Objective — was to study the placental activity of pro- and antioxidant enzymes, as well as to evaluate the expression of proteins that regulate redox processes during physiological pregnancy and placental dysfunction. Material and methods. The study included 60 women who made up 2 groups. The 1st (control) group is represented by 28 women with physiological pregnancy. The 2nd (main) group included 32 women with placental dysfunction. The activity of prooxidant enzymes NADPH oxidase and xanthine oxidase, antioxidant enzymes superoxide dismutase, catalase, glutathione-dependent enzymes and lipid peroxidation products were determined by spectrophotometric and fluorimetric methods. Differentially expressed proteins were detected and identified by two-dimensional electrophoresis and MALDI-TOF mass-spectrometry. Results. Placental dysfunction is accompanied by an increase in the activity of prooxidant enzymes and a decrease in antioxidant. A correlation between the studied enzymes and lipid peroxidation of products was established in different directions (depending on their redox properties). Expression of 3 proteins that regulate redox processes and energy metabolism in mitochondria — dienoyl-CoA-isomerase, citrate synthase, prohibitin — with placental dysfunction is reduced and 1 protein (a-ketoglutarate dehydrogenase mitochondrial) is increased, which has a compensatory significance. Conclusion. Formation of dysfunction of the placenta is accompanied by a violation of placental redox processes both enzymatic and nonenzymatic nature. The revealed changes obviously play a pathogenetic role in the formation and further development of dysfunction of the placenta.