For over half a century Davidson has informed and educated students, doctors and other health professionals all over the world. The 20th edition of this concise yet comprehensive text lives up to its reputation for providing a rational and easily understood basis for the practice of medicine. Davidson has always linked the pathogenesis of disease with the practice of clinical medicine, serving the needs both of students and of more experienced readers requiring ta be brought up to date with rapidly advancing medical sciences. The first section on the 'Principles of Medicine' describes the fundamental mechanisms determining health and disease, while the second, the 'Practice of Medicine', covers practice in the medical specialties to MRCP(UK) level. The book's global perspective has been enhanced by the input of its International Advisory Board and new authors from outside the UK. There is now a more detailed account of health problems in the developing world. For the benefit of all readers, both SI and non-SI units are now quoted.