Epidemiologic studies have demonstrated that almost half those infected with HIV will develop AIDS within 10 years, and the proportion rises with each year. Disturbing personal and professional ethical issues have surfaced, including the appropriateness of treatment in the terminal stages of illness, the limits of confidentiality of medical information, and even the refusal of some health-care workers to care for patients. AIDS is a particularly difficult and devastating disease because of the nature of the disease itself, the fact that it afflicts mostly young people and is at epidemic proportions, and the fear of transmission, particularly among health-care workers. AIDS is deeply rooted in our views of the social worth of individuals and the acceptability of behavior and thus it forces society, particularly physicians, to confront its own vulnerability and inability to substantially alter the power and force of natural events. The principles of clinical care for AIDS and HIV infection are discussed. 38 notes.