This paper has as intention to show to the existence of the asymmetry of the information as a failure of the market, frequents in the benefit of the services of health and, in which there is a necessity of intervention of the State for the correction of such situation. At a first moment a brief review will become of the transforamtion of the sector health in Colombia, in which the mercantilista behavior is evident that it has had the sector through the time. Secondly, a small approach to the concepts os supply and demand appears, and the concept of asymmetry of the information is introduced, itself, soon to show the different types from asymmetry that have demostrated in the sector health. Finally, some related annotations become.