Acute myocardial infarction (AMI) is a scarce but fatal complication in Graves' disease (GD). Silent myocardial infarction (MI) associated with GD has never been reported. A 37-year-old male patient was admitted due to poorly controlled hyperthyroidism and persistent fever. But the patient did not complain of chest pain on admission. The electrocardiogram (ECG) showed Q waves and ST-segment elevations. Cardiac troponin I (cTnI) was sharply increased. He was qualified to an emergency coronary angiography which showed normal coronary arteries without any stenosis. The potential mechanisms for AMI with angiographically normal coronary arteries in the setting of hyperthyroidism may be attributed to the hyper-metabolic state due to thyrotoxicosis, severe vasospasm in coronary artery, coagulation abnormalities, and the inflammatory/autoimmune milieu. In conclusion, patients with GD-associated silent MI are unusual. Early recognition and diagnosis by clinicians provide a better prognosis. This case demonstrates the importance of ECG and cTnI screening among GD patients. (C) 2018 Elsevier Inc. All rights reserved.