This book attempts to give a symptom- rather than a disease-oriented approach to differential diagnosis. It is intended for students, for postgraduates studying for higher examinations, and for all those who wish to refresh themselves on common problems in internal medicine. All chapters have been reviewed and revised, including new aids to diagnosis an new screening techniques, eg NMR, echo and ultrasound. In addition, there is discussion on AIDS and more information on the management of coronary artery disease. Each chapter discusses a common symptom or sign. It attempts to relate this to normal and abnormal function so as to give a basis for understanding. The clnical features which are important in the differential diagnosis are emphasized and there is a discussion of those investigations which will help to establish the diagnosis. Subjects have been selected which are either important in the day-to-day practice of general medicine, or which are poorly understood by students and postgraduates. At the end of each chapter there is an illustrative case history with questions. This is followed by a detailed discussion of the case. These problems serve as a challenge to the reader's diagnostic ability and as a test of comprehension of the chapter. They should be of value to those taking the MRCP(UK) examinations which contain this type of case problem. Since the second edition in 1982, HIV infection and AIDS have become important health problems. Like syphilis in the past, these disorders must now be considered in the differential diagnosis of disease affecting many systems of the body. Diagnostic methods continue to increase in sophistication and power, while at the same time becoming progressively less invasive. The newer imaging techniques in particular have revolutionized the approach to many diagnostic problems. It has, therefore, been necessary to make considerable changes in this third edition so that these new and exciting developments can be given due weight and their incorporation into diagnostic protocols clearly demonstrated.