* Introduction * Chagas' disease * Chemotherapy * Immune response in experimental T. cruzi infection * Immune response in human beings infected with T. cruzi * Immune response in the treatment of chagasic infection * The need for new therapeutic alternatives for Chagas' disease * Conclusions The final decade of the 20th century was marked by an alarming resurgence in infectious diseases caused by tropical parasites belonging to the kinetoplastid protozoan order. Among the pathogenic trypanosomatids, some species are of particular interest due to their medical importance. These species include the agent responsible for Chagas' disease, Trypanosoma cruzi. Approximately 8 to 10 million people are infected in the Americas, and approximately 40 million are at risk. In the present review, we discuss in detail the immune mechanisms elicited during infection by T. cruzi and the effects of chemotherapy in controlling parasite proliferation and on the host immune system.