From June 1984 to July 1992, 392 xenodiagnostic tests were applied on 264 patients with chronic Chngas disease from Brazilian endemic ureas of Virgem da Lapa and Coronel Murta, situated in the Jequitinhonha Vulley, in the State of Minus Gerais. The susceptibilities qflhodnius neglectus, Panstrongylus megistus, Triatoma vitticeps andTriatoma infestans were compared. Most of the time 20 nymphs (fourth instar) of each species were applied to 161 women and 103 men aged between 5 and 83 years of age. The tests were prepared to compare the susceptibilities of two species at a time, using the samepatients,for each test. Results showed a xenopositiveness of 26.28% (103 tests) being 27.98% in women (68positive in 243 applied tests) and 23.49% in men (35 positive in 149 applied tests). The relative frequency of xenopositiveness displayed a great superiority of P. megistus and T. vitticeps. In tests from type I, for example, P. megistus was the unique responsible for 10.730% ofpositive xenodiagnosis vs. only 0.98% in T. infestans. Other parameters analized in this work confirm this superiority, and corroborate that T. infestans can be replaced by P. megistus and /or T. vitticeps in order to upgrade the efficacy ofxenodiagnosis.