We present a case of an uncommon viral myopericarditis in a 19-year-old man with chest pain. Electrocardiographic abnormalities and elevated cardiac enzymes were present. Myopericarditis of unknown origin was diagnosed following cardiac magnetic resonance imaging. During admission, the patient developed tonsillitis and serology tests confirmed an acute Epstein–Barr viral infection. Therefore, in acute myo(peri)carditis, we suggest early viral determination.