ST-segment elevation myocardial infarction (STEMI) can be caused by coronary artery vasospasm (VSA) due to endothelial dysfunction. However, the clinical role of endothelial function tests in VSA-induced STEMI is not fully understood. We present the case of a 43-year-old woman with atypical chest pain and no coronary risk factors. STEMI caused by VSA was diagnosed. Flow-mediated vasodilatation (FMD) and EndPAT tests were performed; the FMD and reactive hyperaemia index were 3.8% and 1.23, respectively. Endothelial dysfunction is the putative cause of STEMI. FMD and EndPAT tests might be useful for predicting adverse outcomes in young premenopausal women with VSA.