The field of minimally invasive therapy (MIT) raises many important issues for the future of health care. It seems inevitable that MIT will replace much conventional surgery. This trend is good for society and good for patients. The health care system, however, may find the change disruptive. The need for hospital beds will shrink. Day surgery and community care will grow. Physicians will have to have special training in doing the new procedures. New organizational forms of care will evolve. Quality assurance procedures will be needed to assure that out-of-hospital care is safe and effective. One negative consequence of MIT is that the indications broaden, so that many 'preventive' procedures may be carried out. Societies are doing little to face up to these changes. The potential of MIT could be enhanced by active policy interventions, including evaluation and attention to the organization and financing of health care.