The protective effects of lobenzarit disodium against the toxicity of allyl alcohol were investigated in vitro using isolated rat hepatocytes and in vivo using mice. In mice, at i.p. doses of 25, 50 and 100 mg/kg lobenzarit significantly decreased the activity of alanine amino transferase (ALT) in serum and the concentration of malondialdehyde (MDA) in liver homogenates, both of which were increased by allyl alcohol at a dose of 64 mg/kg. At concentrations of 0.2 and 0.3 mM, lobenzarit reduced the release of lactate dehydrogenase (LDH) and the levels of malondialdehyde (MDA) induced by 0.4 mM of allyl alcohol in isolated rat hepatocytes. However, lobenzarit did not increase the levels of reduced glutathione (GSH) depleted by allyl alcohol in any of the two experimental models. The protective effects of lobenzarit were dose- and concentration-dependent and they were most obvious when lobenzarit was administered 30 min before allyl alcohol. It is concluded that lobenzarit exerts the observed protective effects most likely by its antioxidant properties.