The past twenty years have seen a steady increase in the number of viruses, of both man and animals, that predispose to the development of cancer. The mechanisms involved are now being elucidated and the means of intervention seem, at least in some instances, close at hand. This volume reviews the current knowledge of oncogenic viruses, their mechanism of action and the prospect for vaccination or therapy. Whilst the emphasis is on viruses of man - papillomaviruses, Epstein Barr Virus, Hepatitis B Virus and Human T cell Leukaemia Virus - the impact of animal studies is recognised by the inclusion of five chapters on oncogenic viruses of animals.