In the treatment of chronic liver diseases adequate therapy can be chosen only in the knowledge of pathogenetic processes. In the liver diseases caused by oxidative stress (alcoholic and non-alcoholic fatty liver and steatohepatitis, drug and compound induced liver toxicity) the antioxidant drugs, like silymarin, in chronic hepatitis caused by hepatitis B and hepatitis C virus, combined peginterferon and nucleosid treatments are the primary therapy modalities to be selected. The main effects of silymarin are the membrane stabilising and antioxidant effects, it is able to help the liver cell regeneration, it can decrease the inflammatory reaction and inhibit the fibrogenesis in the liver. These results have been established by experimental and clinical trials. According to open studies, the long administration of silymarin significantly increased the survival time of patients with alcohol-induced liver cirrhosis. Recently it was demonstrated that high-dosage silibinin infusion treatment could significantly decrease the number of hepatitis C viruses after four-week application. On the basis of the results with the methods of molecular biology, silymarin is able to decrease significantly tumor cell proliferation, angiogenesis as well as insulin resistance. These results support the administration of silymarin preparations in the therapy of chronic liver diseases, especially in alcoholic and non-alcoholic steatohepatitis in current clinical practice, and as it can be awaited, also in the future. In some neoplastic diseases they could also be administered as adjuvant therapy.