Russas, as some others regions of the State of Ceará, has receivedsome attention and a great deal of investigation about the Chagas' disease problem. In 1959 the rate of human infection was 11.6%. Recently a survey was made and high rates of infection in dogs and cats were found. Now we selected in the previousiy region a micro-area (Boa Vista Farm) where we had examined 52 dogs and 21 cats and 11 dogs and 10 cats were infected by T. cruzi. In the same area we have examined another 12 dogs and 10 cats and the global rate of Infection in these animais appeared higher than before: 29.5%. In the same micro-area we performed complement fixation tests and xenodiagnosis in 125 pefsons (50% of the population) and found 7.2% of positivy. AH the persons with positive results, except for one person, have in their homes 1 or 2 animais with positive examinations. 405 triatomines were captured in and outside the houses of the area and 27.7% of them were found to be infected. Triatoma brasiliensis was the most prevalent (93.5%) species and it was found inside the houses in a rate of 52.5% with 30.2% rate of infection. T. maculata was the second species in prevaience (5.4%): 72.8% were captured outside of the houses, 25% of them were infected. 8 specimes of P. megistus were captured outside of the houses and 5 of them were infected. 4 rodents out of 10 captured (Rattus rattus) were found to be infected and also 1 out 3 opossum (Didelphis azarae). The Authors have got the conclusion that domestic and para-domestic cycles of transmission are being developed in the micro-area surveyed.