Introduction: Pelvic venous insufficiency (PVI) presents a significant clinical challenge due to its high prevalence, severity of clinical manifestations, and risk of resulting reproductive disorders. Data suggests that PVI progression in women is accompanied by nonspecific reaction changes. The aim of this study was to evaluate lipid peroxidation reaction activity and antioxidant defense mechanisms in ovarian venous blood in patients with various stages of PVI. Methods: A total of 137 women of reproductive age with diagnosed PVI were separated into 3 subgroups (disease stages I, II, and III). The control group consisted of 30 women with overall good health. Blood sampling was performed in both groups of patients from the right and left pelvic ovarian veins. Spectrophotometry, spectrofluorometry, and enzyme immunoassays were used for investigation, and statistical analysis performed. Results: Patients with PVI stage I had higher levels of CDs and TBARs, as well as increased SOD, catalase, and GPO activity in both ovarian veins, compared to the control group. Patients with PVI stage II had higher LH, CDs, and TBARs, and reduced GSH in both ovarian veins compared to the control group. PVI stage III in the right and left ovarian veins was characterized by high levels of LH, CDs, and TBARs, and GSH deficiency (7 and 8.29 times lower, respectively) compared to the control group. There were no significant differences in these parameters between the right and left ovarian veins. Conclusion: Lipid peroxidation reaction activity and levels of antioxidant defense components in the right and left ovarian veins of patients with PVI demonstrate similar patterns across all stages of PVI. The imbalance between lipid peroxidation activity and antioxidant defense systems increases with disease progression from stage I to III. Monitoring changes in the LPO-AOD system in patients with PVI is an important component of preventive measures in the early stages of the disease, and could be used as pathogenetic treatment to limit disease progression.