From 1982 to 1986, investigations on the natural infection with leishmanias of the sylvatic and commensal mammals were carried out around the city of Jacobina, Bahia, one of the oldest endemic foci of visceral leishmaniasis in Brazil. The species of Marsupialia Didelphis albiventris predominated, with the rate of 44%, over the total of 213 specimens belonging to only 11 different species of mammals collected there. Among the 84 specimens of D. albiventris examined, 2(2.3%) were infected with Leishmania donovani sensu lato; 1 with L. mexicana amazonensis, 1 with L. braziliensis sub species, and 3 with Trypanosoma cruzi. Also, amastigote suspected bodies were seen in the smears of spleens and livers of 3 Dasyprocta aguti, 1 Cercomys cunnicularius and 1 Oryzomys sp. Although strengthened by some epidemiological evidences, such as specific predominancy, peri domestic and domestic occurrence, attractivenessfor the vector Lutzomyia longipalpis and the concomitancy with human cases of visceral leishmaniasis at the same place, the low rate of the natural infection of D. marsupialis still do not allow a definitive conclusion that the oppossum is a primary and the most important reservoir of visceral leishmaniasis in Jacobina.