The present work was based on the observations that, as regards health care costs, the major problem in most present systems is that those who are responsible for the treatment decision (physician and patient) do not bear a direct financial responsibility for it, and that the overall system is very fragmented, which leads to numerous externalities. In accordance with this diagnosis, a reform strategy should particularly aim at creating units which are responsible for the provision and the financial coverage of comprehensive health services to a given population. Health Maintenance Organizations (HMOs) are a private economy oriented solution in this direction. They have proved to be a real possibility in the USA over years, at least for part of the population, and show interesting performances as regards costs. They were able to develop and evolve in the largely open US institutional framework. In Switzerland, we have more strongly structured systems, which appear to stand in relative contradiction to the HMO solution. A potential adaptation of the concept to our country would therefore require a preliminary in depth discussion about the meaning of the present collective (insurance) contract structure, the position of hospitals in a private economy health care system as well as about the conditions of the sought for competition in the HMO model.