The most important health-care development of the day is the recent, relatively unheralded rise of a huge new industry that supplies health-care services for profit. Proprietary hospitals and nursing homes, diagnostic laboratories, home-care and emergency-room services, hemodialysis, and a wide variety of other services produced a gross income to this industry last year of about $35 billion to $40 billion. This new "medical-industrial complex" may be more efficient than its nonprofit competition, but it creates the problems of overuse and fragmentation of services, overemphasis on technology, and "cream-skimming," and it may also excercise undue influence on national health policy. In this medical market, physicians must act as discerning purchasing agents for their patients and therefore should have no conflicting financial interests. Closer attention from the public and the profession, and careful study, are necessary to ensure that the "medical-industrial complex" puts the interests of the public before those of its stockholders. (N Engl J Med. 1980; 303: 963–70.)