Introduction: in the emergency room, chest pain is the second cause of consultation after trauma. The symptoms in order of frequency are: musculoskeletal, cardiovascular, respiratory, gastrointestinal and others. Case presentation: a 29-year-old man with oppressive precordial pain of seven hours of evolution; the ECG reported a subepicardial lesion of the inferior face. Acute myocardial infarction of the inferior face vs pericarditis was considered. Anti-ischemic therapy was initiated. The echocardiogram showed a discreet increase in the refractivity of the pericardium adjacent to the inferior wall of the left ventricle and preserved biventricular function. The evolution was satisfactory and was discharged at 72 hours. Conclusions: in the case of chest pain in the emergency department, pericarditis and myopericarditis should be considered, whose diagnoses are based on the clinical history, the ECG, the biomarkers and the transthoracic echocardiogram. Early diagnosis and timely management reduce complications. Abbreviations: 1AM, myocardial infarction; ECG, electrocardiogram.