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 the myocardial enzyme profile is the creatine kinase isoenzyme, CK-MB, because it is mainly from the injured myocardial cells and is myocardial specific. Therefore, if only CK-MB is elevated without other enzymes, myocardial injury and myocarditis are not necessarily present; conversely, elevation of other enzymes with normal CK-MB does not support myocarditis, as these enzymes can also originate from many other tissues such as skeletal muscle and liver. In addition, infants and children can have higher levels of normal cardiac enzymes than adults due to active cellular metabolism, and the binding during venous blood sampling and the child’s resistance can cause elevation of non-specific myosin; there is also the issue of sensitivity and accuracy of the assay, currently most hospitals in China test for CK-MB activity in IU/L, while some tertiary hospitals carry out CK-MBmass (mass) Therefore, it is recommended that children with mildly elevated CK-MB can have their CK-MBmass tested again, and most of the test values will be in the normal range, thus relieving the concern of myocarditis. 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, because the clinical manifestations of myocarditis are non-specific and mild, it is important not to miss the diagnosis, especially not to miss the diagnosis of severe myocarditis, which can lead to serious consequences.