According to the Dallas criteria, myocarditis is defined histologically as an inflammatory process involving the myocardium with an inflammatory infiltrate and myocyte necrosis or damage. Clinically, myocarditis is an insidious disease that is usually asymptomatic and commonly underdiagnosed. Infact, the symptoms are often non-specific and the majority of cases recover fully with no sequelae. At present, endomyocardial biopsy remains the gold standard for the diagnosis of myocarditis, despite its limited sensitivity and specificity. However, the lack of an association between biopsy evidence of myocarditis and the presence of autoantibodies in patients with clinical signs of myocarditis, the paucity of the positive biopsy findings in large cohorts of patients with suspected myocarditis, the potential discordance between clinical and histologic features and the inherent limitation of histologic diagnosis, suggest that the diagnosis shouldn't be based on histologic examination alone. The magnetic resonance imaging (MRI) with gadolinium can be useful to visualize the localization, activity and extent of inflammation and may be a powerful noninvasive diagnostic tool in acute myocarditis. Infact, MRI achieves a 100% sensitivity and a 90% specificity. We report the case of a 31-year-old male patient with an acute myocarditis with electrocardiographic manifestations like to acute myocardial infarction, whose diagnosis was based on the clinical signs and on the characteristic pattern of the MRI with paramagnetic contrast. The MRI with gadolinium is suggested as noninvasive study to support the diagnosis of acute myocarditis in the correct clinical setting.