Acute Myocarditis (AM) is an inflammatory disease of the myocardium with a great heterogeneity of clinical presentations. Retrospective study including all patients (P) with a discharge diagnosis of AM between 2010 and 2013. 65 P had a diagnosis of AM (62 idiopathic, 2 acute viral and 1 drug-induced), they were more likely males (n=60) and the majority (n=44) were in the 2 nd and 3 rd decade of life. Cardiovascular risk factors were present in 58,5%, but only 12,3% had >1 risk factor. Chest pain was the most common clinical presentation (n=64). A prodome of fever/constitutional symptoms occurred in 43,1%. About half of the P(n=34) had pericarditis and 26,2% had pericardial effusion. At admission, 31% had signs of heart failure. Admission electrocardiogram showed repolarization abnormalities in 75,4%, with persistent ST-T segment elevation being the most common (n=33). Pathological Q waves were present in 4,6%. At admission, 92,3% had increased inflammatory biomarkers. Virus serology was collected in 27,7%, and only in 2P the results were suggestive of acute infection. The echocardiogram showed left ventricular (LV) systolic dysfunction (LVSD) in 18,4% and LV dilatation in 3,1%. About half of the P (n=31) had segmental wall motion abnormalities, more frequently observed in the inferior wall (n=13). Cardiac magnetic resonance (CMR) showed LVSD in 10,5%. Comparing to previously echocardiographic assessment (mean 5,6±6,5 days), CMR showed deterioration of LV systolic function in 3 P and recovery in 8 P. Late gadolinium enhancement (LGE) was localized to subepicardial regions in 63,2%, to mesocardic regions in 8,8% and in 21,1% was localized in both regions. LGE was most frequently found in the lateral wall (n=44). Regional edema was observed in 5,3%. Endomyocardial biopsy was not performed in any P. During hospitalization, there was no mortality. AM appears as young adult disease frequently presenting with chest pain and often associated with pericarditis and viral prodrome. About one fifth of the P had LVSD, but in-hospital prognosis was relatively benign.