Leishmaniasis comprises a group of diseases caused by different species of parasites of the genus Leishmania. It is widely accepted that cell mediated immune response plays a major role in the development of this disease, and most experimental evidence indicates that CD4+ T cells are the primary, but not the only population of cells involved in the evolution of this infection in the mouse and, perhaps, in the human being as well. There is currently no commercial vaccines aimed to prevent L. m. mexicana infections in humans. Although, experimental murine infection induced with Leishmania could be prevented by previous inoculation of attenuated parasites or purified molecules.