Infections must be thought as one of the most important, if not the most important, risk factors for cancer development in humans. Progress has been particularly rapid in this field over the last 25 years and today we can report that approximately 20% of the global cancer incidence is initiated or promoted by infectious events. In the early 1980s, the author of this work and his co-workers made the connection between HPV infection and cervical cancer. Subsequently scientists all over the world discovered tumor-inducing bacteria, viruses, parasites, and protozoons, opening up entirely new prospects for the prevention and treatment of infection-induced cancer by vaccination. Adopting a unifying concept and a consistent structure for the individual chapters, Professor zur Hausen provides a thorough and comprehensive overview on cancer-inducing infective agents -- viruses, bacteria, parasites and protozoons -- and their corresponding transforming capacities and mechanisms. He does not cover the structure and molecular biology of the agents presented in great detail, but rather concentrates on those aspects that link the respective agents to human oncogenesis. As such, an extensive bibliography after each chapter permits further studies on the subject. From the contents: Historical review Tumors linked to infections Herpes viruses and oncogenesis Papillomaviruses Hepadnavirus family Flavivirus family Retrovirus family Parasites and human cancer Cancers with a possible infectious etiology With a chapter on Helicobacter written by James Fox of Harvard University, this is an invaluable and instructive reference for all oncologists, microbiologists and molecular biologists working in the area of infections and cancer.