Aflatoxin B(1) (AFB(1)) causes oxidative stress and ROS formation via metabolic activation of AFB(1). Glycyrrhizic acid (GA) has been reported to have antioxidative properties. The present study was to investigate the effect of GA, a major component of licorice on AFB(1)-induced cytotoxicity in human hepatoma cell line (HepG2). GA displayed protective effects against AFB(1) treatment. Both CYP1A1, and glutathione S-transferase (GST) activities were increased in cells after treatment with the GA, while CYP1A2 did not seem to be affected by GA. For cells without GA pre-treatment, cell injury was implicated as indicated by the decrease in cell viability. The time-course study of GA showed pretreatment of cells with GA for 24 h was effective. The treatment of cells with GA and AFB(1) enhanced the detoxifying enzyme activity. The pre-treatment of cells with GA provides protective effects in terms of the enzyme activity and increase in cell viability. The results suggest that GA protects against aflatoxin-induced oxidative stress. This may contribute to its anticarcinogenic capability. The protective effect is likely due to its capacity to inhibit the metabolic activation of hepato-toxin, a critical factor in the pathogenesis of chemical-induced carcinogenicity.