In this study, we compared the effects of two dietary antioxidants, -tocopherol (-T) and β-carotene (β-C) against tert-butyl hydroperxide (tBHP)-induced oxidative stress in human hepatoma HepG2 cells. Cell proliferation, lipid peroxidation (LPO), cellular lactate dehydrogenase (LDH), [3H]-aflatoxin B1(AFB1)-DNA adduct formation, and cytochrome P450 2E1 (CYP2E1) expression were determined after antioxidants were added to the tBHP-stressed cells. When compared to an ethanol-based control, all biomarkers for the cell damage were significantly increased by treatments. Treatments of β-C or the combination of two antioxidants at 50 ppm for 48 h enhanced cell proliferation (P < 0.05) compared to tBHP control. The antioxidative and cytoprotective actions of -T...