With the arrival of summer, the number of children with herpes pharyngitis increases significantly as the temperature rises. Outpatient physicians check for cardiac enzymes along with infection indicators, and elevated cardiac enzymes indicate myocardial damage, and many children are diagnosed with “viral myocarditis” as a result. It is believed that the main causative agent of herpes pharyngitis is coxsackievirus group A (CA), and the main causative agents of viral myocarditis are coxsackieviruses (groups A and B) and adenoviruses. What is “viral myocarditis”? Myocarditis is a disease caused by various infections or other causes of myocardial interstitial inflammatory cell infiltration and adjacent myocardial cell necrosis or degeneration, resulting in cardiac dysfunction and other systemic damage. The most common clinical condition is viral myocarditis. Except for a few cases of fulminant myocarditis where the virus causes direct and extensive destruction of myocardial cells, most viral myocarditis is caused by activation of the body’s immune system due to viraemia, so the occurrence of myocarditis is determined by various factors such as genetics and immunity. Elevated cardiac enzymes are an important basis for the diagnosis of myocarditis in children, but not any elevation in the myocardial enzyme profile supports the diagnosis of myocarditis. The most diagnostic value of myocardial enzyme profile is creatine kinase isoenzyme, CK-MB, because it is mainly derived from injured myocardial cells and has myocardial specificity. In myocardial injury, a variety of other enzymes are released simultaneously, including LDH, HBDH, and CK; therefore, if only CK-MB is elevated without other enzymes, there is not necessarily myocardial injury and myocarditis. Conversely, an elevation of other enzymes with normal CK-MB is even less supportive of myocarditis, as these enzymes can also originate from many other tissues such as skeletal muscle and liver. In infants and young children, normal myocardial enzyme levels can be higher than in adults due to active cellular metabolism, and the binding of blood during venous sampling as well as the child’s resistance can cause elevation of non-specific myosin; there is also the issue of sensitivity and accuracy of the test method. Most hospitals in China currently test for CK-MB activity in IU/L, while some tertiary hospitals carry out CK-MBmass (mass) testing in ng/ml, which is more accurate than activity testing, so it is recommended that children with mildly elevated CK-MB can do CK-MBmass testing again, and most of the test values will be in the normal range, thus relieving the worry of myocarditis. Troponin, a more specific indicator of myocardium, can also be tested to aid in the diagnosis. Another special case is when CK is significantly elevated by thousands or tens of thousands of IU/L, along with other cardiac enzymes, but CK-MB does not exceed 5% of the CK value, which is a sign of myopathy rather than myocarditis, and the child should be advised to consult a neuromuscular disease specialist. In conclusion, the diagnosis of myocarditis is made by combining clinical symptoms and signs with myocardial enzymes, electrocardiogram, and cardiac ultrasound, and should be made in accordance with the diagnostic criteria for myocarditis in children. On the other hand, since the clinical manifestations of myocarditis are non-specific and vary in severity, the diagnosis should not be missed. In particular, the diagnosis of severe myocarditis should not be missed to avoid serious consequences.