In July 1974, 360 blood samples were collected from rural people randomly assembled, in the county of Encruzilhada do Sul, State of Rio Grande do Sul, Brazil: electrocardiograms were performed as well. Complement fixation test (CFT) was perfomed in 350 samples, with 104 positive for Chagas' disease (29,71). 116 out of 360 electrocardiograms showed abnormalities (33,14%) being 41 from the group of 104 individuals with positive CFT (39,42%) e 75 from the group of 246 individuais with positive CFT (30,48%). The difference of 8,49% between the prevalence of abnormalities in CFT positive and negative people, has not statistical significance. Therefore CFT positivity seems not to be strictly related to electrocardiographic abnormalities. The Author makes a comparison between his results and those obtained in the same county in 1954 by Brant et Cols. The conclusion, is that in the meantime there has been a substancial increase in the serological prevalence of Chagas' disease and in the electrocardiographic abnormalities; nevertheless, it seems not to be a surely evident prevalence of abnormalities in individuals with positive CFT