The experiments with passive transfer of splenocytes obtained from animals immunized with Trypanosoma cruzi lysate revealed the role of cell-mediated component of the immunity in the antitumor effect of T. cruzi. The common features of T. cruzi antigens and tumor-specific antigens of Ehrlich's adenocarcinoma were demonstrated. These antigens were shown to have common epitopes with mammalian mucins. The oncoprotective effect was achieved by immunization with type II and III mucins and was reproduced after passive transfer of splenocytes from immunized animals.