The oxidative damage of liver tissue appears to favour a fibrogenic process, through the stimulation of TGF beta 1 and procollagen gene expression. The latter effect has been also showed by a well defined end-product of lipid peroxidation, 4-hydroxy-2,3-nonenal in human Ito cell culture. "In vivo" and "in vitro" data give evidence of a strong down modulation of TGF beta 1 and collagen expression afforded by supplementation with different antioxidant molecules.