Myocarditis in children is not very common, but the state of the disease is similar to viral influenza, making it challenging for a clinician to make an early diagnosis and treatment plan. Elevated levels of inflammatory biomarkers like C-reactive protein, serum lactate, troponin, and abnormal ECG may be helpful for high-index suspicion of myocarditis. This study aimed to determine the predicting factors and outcomes of acute myocarditis in children admitted to a teaching hospital in the Eastern province of Saudi Arabia. Complete medical records of 80 pediatric patients with acute myocarditis over 5 years (from 2015 to 2019) were retrieved, including demographic characteristics, laboratory investigations including cardiac enzymes (serum lactate, CPR, and troponin), and ECG findings for the diagnosis of myocarditis based on tachycardia and bradycardia. There were 22 (27.5%) mortalities that took place during the hospital stay. Low WBC (mmol/dl) levels were associated with in-hospital mortality (p 0.001), whereas high serum lactate levels (>2 mmol) were not. Association of troponin level (0.15ng/mL) was not significantly associated with mortality (p=0.496). The area under the ROC=0.947 (95% C.I: 0.88–1.0) revealed highly significant predictive validity at the 2.3 best cutoff point, having 90.9% and 87.9% sensitivity and specificity, respectively. Clinical factors and elevated biomarkers were associated with poor prognosis and in-hospital mortality in pediatric myocarditis. Serum lactate and troponin levels demonstrated high predictive validity for early diagnosis.