The protective effect of sodium tetraborate on chromium-induced hepato-and genotoxicity was investigated. The experiment was performed on Wistar rats divided into 4 groups: I-control, II-during 5 days received sodium tetraborate (4.0 mg/kg/day) orally, III-once intraperitoneally dichromate potassium (0.33 LD 50), IV-preliminarily during five days sodium tetraborate orally and the last administration was combined with a single intraperitoneal injection of potassium dichromate (0.33 LD 50). The introduction of potassium dichromate increases the activity of liver marker enzymes in the blood serum, the number of polychromatophilic erythrocytes (PCE) with micronuclei (MN) in the bone marrow, the malonic dialdehyde in the liver tissues, and decreases the catalase activity and glutathione content in the hepatic tissue. In the group receiving sodium tetraborate there is a tendency to decrease in the blood serum the activity of marker liver enzymes, the number of micronuclei in PCE, inhibition of lipid peroxidation (LP) and activation of the antioxidant status in the liver. In the fourth group, the preventive use of sodium tetraborate inhibited the development of cytolysis, cholestasis, LP and had a hepatoprotective, antimutagenic effect.