The study is aimed at determining the etiopathogenesis of reproductive ability disorder among high-producing cows. For this purpose, a group of cows amounting 37 heads was formed following the principle of analogous pairs. The cows were inseminated during the first estrum after calving, and then their blood was drawn using Monovette system taking into account sterility terms. In the drying off period, the blood was drawn 1-4 days before calving and during the first day after calving. Totally 253 blood samples were tested. Proceeding from the results, cows were divided into two groups. The first group included 20 cows impregnated after the first insemination; the second group included 17 not impregnated cows. Later the blood was drawn providing for the parturition process and postpartum period. Blood values were investigated by commonly accepted methods using certified equipment. The study showed that cows during the early gestation have lipid metabolism, lipid peroxidation and antioxidant system state significantly differing from those among non-pregnant cows. During the gestation, cows have the level and class of general lipids reducing, as well as the accumulation of lipid peroxidation products. Cattles with retained placenta have low lipid metabolism and higher level of peroxidation within interlactation period. After the calving, this difference tends to widen. The obtained data can be used for elaboration of measures preventing post-parturient complications by applying agents with antioxidant properties.