Hepatocellular carcinoma (HCC) is the fifth most frequent neoplasm worldwide (> 500,000 deaths/year), and in some areas of the world it represents the primary cause of cancer-related death (Parkin et al., 2001). Years ago, HCC was considered a major health problem in Asia and Africa, with minor prevalence in Europe or America. However, current data indicate that its incidence is steadily increasing in the West (Parkin et al., 2001). This has raised the attention paid to its molecular pathogenesis and to aspects related to epidemiology and treatment. This focus summarizes the established knowledge regarding these issues and points out the most active areas of research where strong data are eagerly awaited.