Wellens' syndrome (WS) is a pattern of electrocardiographic (ECG) T-wave changes associated with critical narrowing of the left anterior descending artery. ECG changes are described as deeply-inverted or symmetrical or biphasic T waves in V2-V4. T wave changes in the syndrome usually occur during a pain-free interval. The origin of these changes is unclear. These T wave changes are the sign of preinfarctional state and can progress to myocardial infarction. Coronary angiography should be planned for patients presenting with this syndrome without performing provocative tests. There is an increased risk for morbidity and mortality in the absence of urgent coronary revascularization. Although WS is frequently encountered in the daily clinical practice, it is rarely described in cardiology books. Our aim was to point out the clinical importance of WS. We report the case of a 44-year-old male patient who presented to the emergency department with WS.