We report the case of a 20-year-old healthy male who developed acute myopericarditis 2 days after receiving the second dose of the mRNA Pfizer-BioNTech COVID-19 vaccine. The course of the disease was mild and the patient was discharged after a few days of hospitalization.Recently, several case reports involving myopericarditis in patients who received an mRNA vaccine against SARS-CoV-2 have been published and the U.S. Centers for Disease Control and Prevention and the European Medicines Agency pharmacovigilance risk assessment committee are currently investigating an overall increased number of cases. They are also assessing whether there is a higher incidence than expected in vaccinated young adults and teenagers, especially males. Although a clear causal link has not been proven at this time, physicians should be aware of such potential adverse event, taking into account the increasing number of young people that will receive mRNA vaccination over the next few months.