During the late 70's and early 80's in Mexico, as in the rest of Latin-America, sanitary policies were directed to support the growth of the private sector of health care at the expense of the public sector. This work analyzes the evolution of the health insurance market as a part of the privatization process of health care. The analysis based on economic data, provides the political profile behind the privatization process as well as the changes in the relations between the State and the health sector. The central hypothesis is that the State promotes and supports the growth of the private market of medical care via a series of legal, fiscal and market procedures. It also discusses the State roll in the legal changes related to the national insurance activity. A comparative analysis is made about the evolution of the insurance industry in Argentina, Brazil, Chile and Mexico during the period 1986-1992, with a particular enfasis in the last country. One of the principal results is that the Premium/GNP and Premium/per capita, display a general growth in the 4 countries. This growth is faster for Mexico for each one) because the privatization process ocurred only during the most recent years. For the 1984-1991 period in Mexico the direct premium as percentage of the GNP raised from 0.86% to 1.32%. If one focussed only in the insurance for health and accidents branches the rice goes form 8.84% in 1984 to 19.08% in 1991. This indicates that the insurance industry is one of the main targets of the privatization process of the health care system in Mexico. This is also shown by the State support to fast expansion of the big medical industrial complex of the country. Considering this situation in the continuity of the neoliberal model of Mexico, this will profound the inequity and inequality.