Viruses are the causes of approximately 25% of human cancers. Due to their importance in carcinogenesis, there is a desperate need for a book that discusses these viruses. This book is therefore timely, providing a comprehensive review of the molecular biology of oncogenic viruses and the cancers they cause. Viruses that are discussed in the individual chapters include hepatitis B virus, hepatitis C virus, human papilloma viruses, Epstein-Barr virus, Kaposi’s sarcoma virus and human T-cell leukemia virus type 1.This book provides up-to-date information for graduate students, postdoctoral fellows, medical students, physicians and non-experts who are interested in learning more about the oncogenic viruses and how they cause human cancers.