Silymarin is the main component of milk thistle. In recent years it has been used in the treatment of liver injury induced by acetaminophen, CCL4, ethanol and amanita mushroom. Also it is used for treatment of cancer and infertility and reducing the adverse reaction of chemotherapy and hemolysis due to oxidant agents. Silymarin was found to modify the functions related to receptors, enzymes and transporters in cells. Some of its effects are increase activity of glutathione peroxidase and superoxide dismutase, upregulation the P53 gene expression, decrease the production of leukotriens, tumor necrotizing factor (TNF), nitric oxide (NO) and reduce the activity of P-glycoprotein and nuclear factor.