Most HIV-positive patients with AIDS are at great risk of developing a variety of infectious and noninfectious pulmonary complications. Many of these are rapidly lethal if untreated and the most important, such asPneumocystis carinli, tuberculosis, and fungal infections are discussed in considerable detail. As the treatment results of these early complications improve, AIDS patients now survive long enough to develop further pulmonary complications as well as secondary cardiac and cardiovascular problems. The incidence, diagnosis, prevention, and treatment of all aspects of this complex illness are then broadly reviewed. Complications of current therapy are also discussed.