Serological tests of fluorescent antibodies, hemagglutlnation, and complement fixation fo Chagas' disease were performed in 1609 cases. In 154 cases the three tests were positives, with a rate of 9,57%. Furtherly 50 serologioally positive patients were examined by means of xenodiagnosis. Rates found were of 56% upon the number of serologioally positive and of 5,35% upon 1609 persons examined. Attention is called on the high incidence of Chagas' disease at the Hospital São Pedro, besides others remarks.