Kahweol and cafestol significantly reduced t-BHP-induced oxidative injuries in cultured rat hepatocytes, as determined by cell cytotoxicity, intracellular glutathione (GSH) content and lipid peroxidation in a dose-dependent manner. In addition, kahweol and cafestol provided good protection from the t-BHPinduced production of intracellular reactive oxygen species and DNA damage. The in vivo study showed that pretreatment with kahweol and cafestol prior to the administration of t-BHP significantly prevented the increase in serum levels of hepatic enzyme markers (alanine aminotransferase and aspartate aminotransferase) and reduced oxidative stress, such as GSH content and lipid peroxidation, in the liver in a dose-dependent manner. The histopathological evaluation of the livers also revealed that kahweol and cafestol reduced the incidence of liver lesions induced by t-BHP. Taken together, these results support the anti-oxidative role of kahweol and cafestol and demonstrate that kahweol and cafestol can protect hepatocytes from oxidative stress.