The antioxidant activity of reamberin was investigated in patients with FIGO stage III ovarian cancer: 34 patients received intravenous reamberin (Research and Technological Pharmaceutical Firm POLYSAN, Saint Petersburg, Russia) 400 ml of 1.5% infusion solution at a rate of 40—80 drops/min (2—4 ml/min) once daily for 5 days during polychemotherapy; 30 patients received only the latter (a control group). The efficacy of the drug was evaluated by the levels of lipid hydroperoxides, conjugated dienes, and malondialdehyde and by the activity of the main components of the antioxidant system (ceruloplasmin, vitamin E) in the blood of patients. The administration of reamberin to patients significantly reduced the plasma levels of lipid hydroperoxides by 27%, conjugated dienes by 16%, and malondialdehyde by 30% compared with the patients in the control group. An analysis of the effect of succinate-containing drugs on the activity of the antioxidant system components established that the blood concentrations of ceruloplasmin and vitamin E were 68 and 13%, respectively, higher than those in the control group. Thus, the incorporation of reamberin into the treatment of patients with ovarian cancer should be considered pathogenetically justified, clinically reasonable, and promising.