Medical Virology first appeared in 1970 and was immediately hailed as a classic. The Fourth Edition has been completely updated, substantially rewritten, and considerably expanded. Acknowledging that today's students possess a more sophisticated background of molecular and cellular biology, the book is pitched a little higher than was the third edition. Nevertheless, it maintains the exceptionally high standards of the three previous editions, including the now famous user-friendly style. Hundreds of instructive diagrams and succinct tables smooth the path for the reader. Extensive lists of recent authoritative reviews at the end of each of the 36 chapters simplifies the reader's entry into the scientific literature. Throughout, the focus is on fundamental principles, mechanisms and basic facts, rather than on overwhelming detail. Part I of the book, expanded to over 400 pages, comprises in effect a self-contained overview of the Principles of Virology. Part II, entitled Viruses of Humans, deals comprehensively with all the families of human viruses. Extensive coverage is given to the molecular biology of the viruses and of viral replication, pathogenesis and immunity, clinical features of all important diseases caused by all viruses affecting humans, the latest laboratory diagnostic methods, epidemiology and control, including chemotherapy and vaccines. This lucid and concise yet comprehensive text is admirably suited to the needs not only of advanced students of science and medicine but also particularly of postgraduate students, teachers, and research workers in all areas of virology.