“Documento produzido em parceria ou por autor vinculado à Fiocruz, mas não consta à informação no documento”Conselho National de Desenvohnento Cientifico e Tecnológico (CNPq)-BrazilPregnant female mice were infected with Trypanosoma cruzi strains which differed according to several parameters and were classified as three different types. Mice were killed during either the acute or the chronic phase of infection. Animals’ tissues and foetuses together with the placentas, were studied histopathologically. Clear cut differences were noted in the incidence of placental parasitism and in the localization of amastigotes in the vascular sinus of the placenta amongst the animals in the acute phase of the infection with different strains. No parasitism of the foetal tissues was seen. The incidence of placental parasitism reached 98% for the Colombian strain, 18.4% for the Peruvian strain, 17% for the Y strain and 13.2% for the Honmina strain (isolated from a woman that transmitted the infection to twins). The presence of parasites in the vascular part of the placenta was prominent with the Colombian strain and rare with the others. These experimental data seem to show that parasite strain plays a role in congenital T. cruzi infection.