Thus far, a large number of hypothesis have been proposed to explain how ethanol causes liver diseases including fatty liver, hepatitis, hepatic fibrosis, cirrhosis, as well as hepatocellular carcinoma. Although it still remains obscure, recent progress of science enables us to understand the mechanisms more deeply. We reviewed the latest aspects of mechanisms of alcoholic liver diseases, including alteration of redox state, effects of acetaldehyde and acetate, changes of metabolisms of lipid and protein, production of free radicals, alteration of hepatic micro circulation, change of hepatic membrane composition followed by changes of intracellular signal transduction, and effects of endotoxin. Moreover, we discussed the recent progress of studies on enzyme systems which participate in ethanol metabolism.