This paper reviews what has increased medical-care spending bought in terms of health benefits with longitudinal data from the U.S and, more limited, from Spain. Health services contribution to health has been positive in average, especially during the last 50 years for the U.S and the last 30 years for Spain. This contribution differs among countries and is much greater for some diseases (cardiovascular) than for others (cancer). Benefits from health care interventions can be valued on basis on the social willin gness to pay, observed or declared on the process of establishing health policy priorities. 30.000 euros per Quality Adjusted Life Year could provide an efficiency threshold for financing publicly health services in Spain: Consensus and legitimacy of the political process of establishing health priorities becomes, however, more important than any approximate number. Attention is paid finally to bridging the gap between efficacy (the possibilities given by innovation and resources devoted to health care) and effectiveness (the distance to the frontier) of the everyday working of a health system with its inappropriate care and limited application of the existing knowledge.