Ninety female SHR mice were subcutaneously injected with a single dose of 2 mg benzo(a)pyrene (BaP) dissolved in 0.2 ml of vegetable oil. Since the next day after BaP injection mice were started to treat with mitochondria-targeted antioxidant SkQ1 at the doses of 5 and 50 nmol/kg/day in drinking water. Control animals received tap water. Study was finished by 358th day. Number of tumor-bearing mice increased in all groups exposed to BaP but retarded since 20th week in SkQ1-treated groups in comparison with control. Maximal tumor volume gain was observed in control mice resulting in premature death. By the 30th week of study only 20% of control animals survived, whereas SkQ1 treatment increased survival up to 30% at the dose of 5 nmol and 40% at the dose of 50 nmol. By the 40th week mean tumor volume in 5 and 50 nmol SkQ1-treated mice was 13 and 21 cm3 respectively, whereas in control--40 cm3. In SkQ1-treated mice pneumonia was observed rarely as compared with controls. It could be supposed, SkQ1 at the doses of 5 and 50 nmol/kg/day retarted BaP-induced soft tissue carcinogenesis in SHR mice.