The effects of SA3443, a novel cyclic disulfide compound, on acute liver injuries induced by carbon tetrachloride (CCl4), D-galactosamine and DL-ethionine were studied in rats or mice. SA3443 (100-300 mg/kg, p.o.) significantly suppressed the increases of serum transaminase activity and liver triglyceride content in the CCl4 or DL-ethionine-induced model. Furthermore, SA3443 (300 mg/kg, p.o.) clearly reduced the formation of hepatic lipid peroxide in CCl4-treated rats. These results indicate that SA3443 protects the liver against acute liver injury.