Tripanosoma cruzi is for the first time recorded infecting Triatoma costalimai captured in Mambaí couty, state of Goiás, Brasil. The isolated strain is easily cultivated on LIT medium. The above T. cruzi strain was inoculated in mice and in Calomys callosus (Rodentia). The infection can be considered mild in those animals. The prepatent period was 9,4 days for mice and 4,8 days for C. callosus. No lethality for C. callosus was observed during the period of observations. The maxima observed parasitemia was: 366.6/5 [cubic milimeters] for mice and 3,750/5 [cubic milimeters] for C. callosus. Pseudocysts were found in muscles cells of both infected rodent species. Cross-immunity tests showed that a previous infection gives resistance against reinoculation with a virulent T. cruzi strain. Nymphs of Dipetalogaster maximus, Rhdnius neglectus and T. infestans fed on infected animals acquired the infection.