The method of chromosome aberration scoring in the bone marrow cells of C57BL/6 mice was used to study the influence of apo-carotene (AC) on the clastogenic effect of intraperitoneal injections of the following two mutagens: cyclophosphamide (CP) in a dose of 30 mg/kg and dioxidine (DN) in a dose of 300 mg/kg. AC was given per os as a food dye E160L (20% oil suspension) in doses of 0.5, 5, and 50 mg/kg (0.1, 1.0 and 10 mg/kg, respectively, on conversion to pure apo-carotene). The experiment was conducted in three variants: in simultaneous injection of the compounds for 24 h, injection of the mutagens for 24 h in 5-day treatment of the animals with AC, and in combined 5-day administration of AC and mutagens and killing of the animals 6 h after the last administration. In all variants a 10 mg/kg dose of AC reduced the clastogenic effect of CP and DN. Moreover, the clastogenic effect of CP was reduced in pretreatment of the animals with AC in a dose of 1 mg/kg, and that of DN when it was combined with AC in a dose of 0.1 mg/kg for 5 days and in pretreatment of the animals with AC in a dose of 1.0 mg/kg.