Background: Acute myocarditis is a disease entity with diverse clinical manifestations and prognosis. However, the initial prognostic predictors remain to be clearly established. Methods: In a total of 73 consecutive patients diagnosed as acute myocarditis, initial presentations and short-term outcomes were analyzed. Results: Of 73 patients, mechanical ventilation, extracorporeal membrane oxygenation and continuous renal replacement therapy were required in 16(22%), 8(11%), 5(7%) patients, respectively. Twenty-five patients presented with fulminant myocarditis. In-hospital mortality occurred in 12 patients(16%). All of them presented with fuminant myocarditis and showed significantly older age (46짹11 vs. 36짹15 years, p<0.05), lower body mass index (21짹2 vs. 23짹3 kg/m², p<0.05), higher initial creatinine level (2.0짹1.7 vs. 1.2짹0.7 mg/dl, p<0.05) and higher maximal CK-MB level (95짹128 vs. 30짹42 ng/ml, p<0.05) than the patients who survived by univariate logistic regression analyses. Multivariate logistic regression analysis revealed that maximum CK-MB level (p=0.026, OR; 0.018, 95% CI; 0.002-0.034) and age (p=0.028, OR; 1.073, 95% CI; 1.008–1.143) are independent predictors for in-hospital mortality. The maximum CK-MB level ���29.5 ng/ml predicted in-hospital mortality with a sensitivity of 83% and a specificity of 73%, and age ���44 years did with a sensitivity of 75% and a specificity of 74% (Fig). Conclusion: Old age and high maximal CK-MB level are short-term poor prognostic factors in patients with acute myocarditis.