The paper gives the results of investigating lipid peroxidation (LPO) and the antioxidant defense system in 100 pregnant women and parturients with miscarriage of infectious genesis. Similar investigations were conducted in 25 pregnant women with physiological pregnancy and 20 healthy nonpregnant women. Threatened miscarriage and premature delivery in the presence of mixed herpesvirus infection are shown to be accompanied by a significant increase in LPO processes with simultaneous failure of the antioxidant defense system. The rate of LPO is directly related to the magnitude of clinical manifestations of miscarriage (threatened miscarriage, premature delivery). Miscarriage in the presence of bacterial infection is attended by LPO intensification with the preserved potential of the antioxidant defense system. The findings suggest that antioxidant defense is diminished in pregnant women and parturients with herpesvirus infections and that antioxidants should be used in the combination treatment of pregnant women.