A 66-year-old woman with a history of hypertension complained about sudden short-term memory loss. On arrival to our outpatient clinic, she was alert and oriented and did not have chest pain or shortness of breath. Neurological and neuropsychological examinations were within normal limits. In light of a transient anterograde amnestic attack and no neurological focal deficit, we clinically diagnosed transient global amnesia (TGA). To confirm whether there was an intracranial lesion or not, diffusion-weighted MRI of the brain was performed, and revealed hyper-intense lesions in the left hippocampus and right corpus callosum. Consequently, the patient was admitted to our hospital on follow-up for suspected cerebral infarction. On day 1, laboratory tests indicated an elevated troponin I level, and electrocardiogram revealed an inverted T wave in the inferior leads. Coronary angiography on day 9 of admission demonstrated severe stenosis of the right coronary artery, leading to a diagnosis of non-ST elevation myocardial infarction. Although TGA itself typically has a favorable prognosis, clinicians should consider potential concurrent painless myocardial infarction in patients with TGA.