Calcium has a significant effect on cells in the myocardium, affecting conduction, intracellular signaling and contraction of muscle fibers. In fact, calcium levels could affect myocardial action potential and affect heart conduction. Hypocalcemia manifest on ECG with arrythmias or QT prolongation, in some extraordinary cases, it could present with variations in the ST segment, which requires the study of differential diagnoses of cardiac origin, such as acute myocardial infarction with ST elevation (STEMI) or pericarditis. We expose a case of a 28-year-old male patient who arrived at the emergency department with chest pain and was misdiagnosed with STEMI, after a complex process finally it was a severe hypocalcemia mimicking acute myocardial infarction.