To the Editor: Christianson and McClure have presented new evidence from the Minneapolis–St. Paul area that a functional marketplace can be achieved through competing health-maintenance organizations (HMO's).1 This alternative to regulatory controls, espoused by Enthoven at a Federal Trade Commission conference in 19772 and subsequently in an article in the. Journal,3 has become an important national health-insurance proposal, the Consumer Choice Health Plan. That Congress has recently jumped on the procompetition bandwagon in health care is seen in the recent amendments to the National Health Planning Act, which require health-systems agencies to encourage competition in places where competitive forces. . .