A significant amount of literature has been published about the health reforms implemented during the last two decades in most post-industrialized countries, but very little analysis has been attempted about the impact on health care systems and medical profession of such reforms. The essay proposes a new model of analysis of the impact of health reforms on the medical profession at three sociological levels: micro, related to the clinical dimension; meso, about the social division of labour; and macro, concerned with the system of structural interactions among the main social actors involved. A synthetic account of the results is given to show how the model was applied in an international comparative research about the changing medical profession in USA and Europe.