Abstract From 1981 to 1988, 404 patients at our institution were found to have acute myocardial infarction. Of them, 18 (4%) had a positive fixation test for Chagas' disease. Patient age ranged from 41 to 80 years (median = 59). Eleven patients were males. Eighteen nonchagasic patients were matched by 2 year age intervals and sex with each chagasic patient. Before acute myocardial infarction, there were no differences between chagasic and nonchagasic patients with regard to the proportion of stable angina, unstable angina and coronary risk factors. Atypical chest pain occurred in 8 of 15 (53%) chagasic patients for whom this information was found in the medical records and in 1 of 18 (5%) nonchagasic patients ( p = 0.003); dyspnea and palpitations occurred in 6 of 15 (40%) chagasic and 1 of 17 (5%) nonchagasic patients ( p = 0.025). There were no differences between chagasic and nonchagasic patients with respect to both clinical characteristics and cardiac complications of acute myocardial infarction. Nonetheless, 4 of 11 (36%) chagasic patients for whom this information was listed in the medical records but none of 16 nonchagasic patients had normal coronary arteries ( p = 0.019). Thus, chagasic patients who develop acute myocardial infarction have some peculiarities both in the clinical profile before the acute event and in the anatomy of the coronary arteries.