AIM: Silymarin is a potent antioxidant, antiinflammatory and anti-fibrogenic agent in the liver, which is mediated by alteration of hepatic Kupffer cell function, lipid peroxidation, and collagen production. Especially, in hepatic fibrogenesis, mast cells are expressed in chronic inflammatory conditions, and promote fibroblast growth and stimulate production of the extracellular matrix by hepatic stellate cells.METHODS: We examined the inhibitory mechanism of silymarin on CCl4-induced hepatic cirrhosis in rats. At 4, 8,and 12 wk, liver tissues were examined histopathologically for fibrotic changes produced by silymarin treatment.RESULTS: In the silymarin with CCl4-treated group,increase of hepatic stellate cells and TGF-β1 production were lower than in the CCl4-treated group at early stages.Additionally, at the late fibrogenic stage, expressions of TGF-β1 were weaker and especially not expressed in hepatocytes located in peripheral areas. Moreover, the number of mast cell in portal areas gradually increased and was dependent on the fibrogenic stage, but those of CCl4+silymarin-treated group decreased significantly.CONCLUSION: Anti-fibrotic and antiinflammatory effects of silymarin were associated with activation of hepatic stellate cells through the expression of TGF-β1 and stabilization of mast cells. These results suggest that silymarin prevent hepatic fibrosis through suppression of inflammation and hypoxia in the hepatic fibrogenesis.