Kunming mice inoculated with hepatoma cell (H22) suspension subcutaneously at their right axilla were administered orally with antioxidants such as vitamine E, beta-carotene, glutamine, kappa-selenocarrageenan and polysaccharide-peptide of coriolus (PSP) solution. It was found that the inoculated hepatoma growth was suppressed to various extents. The two kinds of polysaccharide antioxidants improved non-specific immunity, enhanced the nitrogen monoxide (NO) content in plasma and strengthened the inhibition of hepatoma. Above antioxidants added in the culture of 7721 human hepatoma cells inhibited the cell proliferation and inducedits apoptosis. Meanwhile, the activity of glutathione peroxidase (GSH-Px) in the plasma of mice increased and the content of malondialdehyde (MDA) decreased. H(2)O(2) in low concentration improved the cancer cell proliferation and inhanced the expression of Mn-SOD c-fos and c-jun, but led to cells apoptosis or necrosis in high concentration. The mechanism of antioxidants inhibiting tumor growth and improving cancer cells apoptosis might be that, on the one hand, the antioxidants blocked the free radicals signal transduction on cancer cells proliferation, and on the other hand, they improved the release of NO through enhancing the non-specific immunity, so inhibiting the cancer cells proliferation directly.