Thiosulfonates are characterized by a wide spectrum of biological activity and have effective antimicrobial, antithrombotic, antitumor and antiparasitic effects. However, the use of synthetic sulfur-containing compounds for therapeutic and preventive purposes requires the study of their effect on the protective mechanisms of maintaining homeostasis, the antioxidant status of the body in particular. The aim of the study was to estimate lipid peroxidation process and the state of the antioxidant system in the kidneys, spleen, brain, and muscles of rats under the influence of newly synthesized sulfur-containing compounds of S-alkyl esters of thiosulfonic acids S-ethyl-4-aminobenzenethiosulfonate (ETS), S-allyl-4-aminobenzenethiosulfonate (ATS) and S-allyl-4-acetylaminobenzenethiosulfonate (AATS). Male Wistar rats kept on a standard diet were divided into four groups of 5 animals each: I (control), II, III, IV (experimental). The animals of the control group received additional 0.5 ml of oil and the animals of the experimental groups 0.5 ml of oil solution of thiosulfonate esters once a day. The animals of II, III and IV groups were given ETS, ATS, AATS at the rate of 100 mg per kg of body weight. The lipid hydroperoxides (LPH), TBA-active products, GSH content and activity of SOD, catalase, glutathione peroxidase, glutathione reductase in tissue homogenates were determined. The multidirectional changes of the studied indicators after consumption of S-alkyl esters of thiosulfonic acids for 21 days have been identified and characterized indicating on different degree of inhibition or activation of LPO processes depending on the type of tissue and the structure of thiosulfonate ester. Keywords: antioxidant system, rat tissues, S-allyl-4-acetylaminobenzenethiosulfonate, S-allyl-4-aminobenzenethiosulfonate, S-ethyl-4-aminobenzenethiosulfonate