A 55-year-old Caucasian woman suddenly developed substernal chest pain at rest accompanied by pallor, diaphoresis, nausea, and vomiting. Physical examination was otherwise unremarkable. The resting ECG showed T-wave inversion in all anterior leads which returned to normal 24 h after the onset of the symptoms. The pain was eliminated promptly by sublingual isosorbide dinitrate. "Impending" acute myocardial infarction was diagnosed. Coronary arteriography, however, failed to reveal any change in any major coronary artery but an apical aneurysm of the left ventricle was detected. As the complement-fixation test for Chagas' disease was positive, the diagnosis of chronic Chagas' heart disease was then established. This unusual clinical manifestation of Chagas' disease is thought to be the consequence of a transient imbalance in the cardiac autonomic nervous system, which is considered to play a central role in the pathogenesis of chronic Chagas' heart disease. In addition, the present case may alert clinicians to the thus far neglected atypical chest pain, which is frequently seen in chagasic patients but whose etiology remains obscure.