Primary human liver cancer, of which hepatocellular carcinoma (HCC) is by far the predominant type, is a major cause of cancer death world-wide, accounting for 700,000 deaths per year. The epidemiology of HCC is particular with both geographic and temporal patterns of incidence paralleling exposure to viral etiologic factors. The highest HCC incidence rates are areas endemic for chronic infection with Hepatitis B virus, mainly Asia and Africa. The pathways by which HCC develop are heterogeneous and influenced by a variety of environmental and host factors. This book is dedicated to hepatocellular carcinoma and includes contributions that span various aspects of the disease from epidemiology, mechanisms and viruses, to promising new biomarkers and targets for treatment.