Objective: In this study, diethylnitrosamine (DEN, known as inducer) and 2-acetylaminofluorene (2-AAF, known as promoter) cause early type hepatocarcinogenesis in 2 months old Spraque- Dawley rats. Demethoxyviridin (DMV) and its metabolite 1-- hydroxy - demethoxyviridin (1--hydroxy-DMV) are fungi metabolites with antitumor effects. Here, we determine their effects on antioxidant systems. Methods: The animals were divided into 10 groups: control, or treated with olive oil, DMSO, DMV, 1- -hydroxy-DMV, DEN, 2-AAF, DEN + 2-AAF, DEN + 2-AAF + DMV and DEN + 2-AAF + 1-( hydroxy DMV. Liver tissues were removed under ether anesthesia after 5 weeks of treatment and homogenated for analysis of superoxide dismutase (SOD) inhibition, glutathione peroxidase (Gpx), catalase activity, and malondialdehyde (MDA) level. Results: SOD % inhibition, Gpx and catalase activities were decreased in DEN, 2-AAF and DEN+2-AAF groups compared to control groups. MDA levels were increased in DEN, 2-AAF and DEN+2-AAF, DEN+2-AAF+DMV, DEN+2-AAF+1-( hydroxyl DMV groups compared to control groups. Conclusions: Fungi metabolites appeared effective on antioxidant system in preneoplastic period of hepatocarcinogenesis. *This study was supported by a grant of the Research Foundation of Eski[scedil]ehir Osmangazi University, Turkey.