Much is new in Family Medicine since the last edition of our textbook. For example, not only is the therapy of human immunodeficiency virus (HIV) disease and the acquired immunodeficiency syndrome (AIDS) much different than a few years ago; the epidemiol ogy of the disease has also changed and more than half of the family physicians in a rural state such as Oregon have already managed patients with HIV disease or AIDS. 1 There are new immunization recommendations for children and new antibiotics for the treatment of bacterial infections. Computers are bringing medical informatics and on-line consultation into office practice. Medicare physician payment reform is underway and the reality of rationing medical care has been recognized. There has been a recent increase in student interest in a family practice career,2 coincidental with a Council on Graduate Medical Education (COGME) recommendation that at least 50 percent of all residency graduates 3 should enter practice as generalists. Also there is increasing awareness of the need for a 4 Center for Family Practice and Primary Care at the National Institutes of Health. This all-new fourth edition is intended to present the scientific and practical basis of family medicine with special attention to what's new in family medicine. The emphasis is on how the physician provides continuing and comprehensive care for persons of all ages, with clinical content selected from the perspective offamily physicians. The format ofthe book, like the practice of family medicine, continues to change.