The antioxidant effects of chestnut inner shell extract (CISE) were investigated in a tert-butylhydroperoxide (t-BHP)-treated HepG2 cells, and in mice that were administered carbon tetrachloride (CCl(4)) and fed a high-fat diet (HFD). Pre-incubation with CISE significantly blocked the oxidative stress induced by t-BHP treatment in HepG2 cells (P<0.05) and preserved the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase compared to group treated with t-BHP only. Similarly, the CCl(4)- and HFD-induced reduction of antioxidant enzymes activities in liver was prevented by CISE treatment compared to control groups. Furthermore, hepatic lipid peroxidation were remarkably lower (P<0.05) in the CISE-treated groups with t-BHP or HFD. To determine the active compound of CISE, the fractionation of CISE has been conducted and scoparone and scopoletin were identified as main compounds. These compounds were also shown to inhibit the t-BHP-induced ROS generation and reduction in antioxidant enzyme activity in an in vitro model system. From these results, it was demonstrated that CISE has the ability to protect against damage from oxidative stressors such as t-BHP, CCl(4) and HFD in in vitro and in vivo models. The CISE might be useful for the prevention of oxidative damage in liver cells and tissues.