The recent panorama of medical practice regulation in Mexico is exposed. The dynamics of regulation changes is observed in different areas, with particular intensity in the labor market. Changes seem to be moving towards the constitution of a new regulatory model. A full state regulation for the last 50 years, is being substituted by a model where private and professional corporations are increasing their influence through informal mechanisms of regulation. In the constitution of this new model, the presence of a wide variety of actors claiming regulatory authority is notorious. Three of these new actors are analyzed: The National Commission for Medical Arbitrage, managed care models of medical services, and Specialists Certification Councils. The changes that have occurred in the process of regulation and its future transformation have an intimate link with the reform of the Mexican health care system (Rev Méd Chile 2001; 129: 1343-50)