We studied 68 asymptomatic subjects (63 men) aged 19-67 years (median age, 41.5 years), who were candidates to donate blood at the University Hospital of the School of Medicine of Ribeirão Preto whose serologic examination result for Chagas' disease was positive. These individuals underwent a resting electrocardiogram (ECG). chest and esophageal radiographic examinations, and esophageal manometry. Thirty-three subjects (49%) had normal esophageal and cardiac examinations. Twenty-eight (41%) had an abnormal ECG and/or abnormal chest radiograph, 18 of them with normal findings on both esophageal manometry and radiograph. Two of the other 10 subjects had normal results on manometry and an abnormal esophageal radiograph. Eight of these subjects had manometric abnormalities which included decreased contraction amplitude (n = 4), failed lower esophageal sphincter (LES) relaxation (n = 1), and simultaneous contractions (n = 3). Esophageal radiographic examination showed no alteration in five cases and esophageal retention in three. Only seven subjects (10%) exhibited exclusive esophageal manifestations, that is, simultaneous contractions (n = 5), simultaneous contractions with failed LES relaxation (n = 1), and esophageal retention (n = 1). Of the total group of 68 subjects, 17 (25%) had some esophageal abnormality observed on manometry (14 cases [21%]) and on radiographic examination (6 cases [9%]). We conclude that asymptomatic subjects with Chagas' disease may have cardiac and esophageal alterations which may be detectable by the examinations regularly used to study heart and esophagus.