Lisosan G is a powder of grain registered as an alimentary integrator. The treatment of rats for 4 days with 0.5 g Lisosan G/kg had no effect on various drug metabolizing enzymes. Experiments in vitro showed that Lisosan G had radical scavenger activity. A confirmation of the antioxidative property of Lisosan G was also confirmed when it was administered in vivo to carbon tetrachloride (CCl4)- intoxicated rats. The toxicity caused by CCl4 treatment of rats was restored to the control levels when the rats were given Lisosan G for 4 days before CCl4. Lisosan G thus does not interfer with drug metabolizing system but has antioxidant properties and protects against CCl4-induced hepatotoxicity.