Hepatocellular carcinoma (HCC) is one of the most common tumors in humans today, and its incidence has been rising over recent decades in Western countries. The main risk factors for the development of HCC are viral infections (hepatitis B and C), alcohol use, and the intake of mycotoxins in some areas of the world. In addition to these risk factors, genetic disorders such as hemochromatosis or alpha1-antitrypsin deficiency play a role. Regardless of the etiology, HCC generally develops on the basis of liver cirrhosis. Various pathomechanisms are effective during the neoplastic transformation of the hepatocyte. In chemical experimental models, hepatocarcinogenesis occurs in three stages: initiation, progression, and promotion. Molecular mechanisms of HCC development include the alteration in growth factor and tumor suppressor gene expression, dysregulation of apoptosis, and occurrence of reactive oxygen species generated during inflammation.