This study considers the introduction of health benefits guarantees in quite underdeveloped health systems, analyzing with more detail the case of Guatemala and briefly, Bolivia. An analysis of Chile is made, showing how the health guarantees imply a partial overcoming of the fundamental duality of the health system. The recent experience of the popular health insurance in Mexico is considered, whose health insurance system is highly segmented. Both the decentralization process and the specific public-private mix play an important role in the organization of the health guarantees.--Abstract