The authors present a serologic and electrocardiographic study performed in a group of one hundred people, ali over 60, living since childhood (95%) or youth (5%) in an area endemic for Chagas' Disease. The complement fixation test showed a 31% positivity in the group. The ECG analysis showed an indiferent distribution of alterations between the individuais with reagent and non-reagent complement fixation test, except for the disorders of stimulus conduction which ivere prevalent in the first group (48.6% and 17,4% respectivelly). The authors concluded that Chagas' Disease, in its cardiovascular form, was most probably presented in this group of old people, a fact that would illustrate the surprising benignity and the long survival that the studied condition may alloiv. This should be expected specially when patterns of RBBB occur isclatelly in the ECG, for that was the most frequent disorder of stimulus conduction observed in the material considered.