Blood samples of animals infected with T. cruzi — Y strain, were submitted to gamma radiation in dosage of 200 and 300 krad. In order to verify the efficacy of this method to eliminante the parasite the blood samples were inoculated in to mice and the following parameters were used: parasitemia, hemoculture, xenodiagnosis, subinoculaticn, reinoculation of mice with a virulent strain and anatomy pathological study. The blood samples exposed to the different radiation dosages and inoculated at two different periods were unable to induce a subsequent infection in all animals tested.