OBJECTIVE: To investigate the value of cardiac troponin I (cTnI) compared with creatine kinase isoenzymes (CK-MB) in the diagnosis and progress of myocarditis in children. METHODS: Serum samples from 38 children with viral myocarditis, 24 children with non myocarditis disease and 22 healthy controls were examined for cTnI by the rapid immunochromatographic test and CK-MB was examined by enzymatic velocity analysis. CVB1-6 IgM was determined using ELISA. RESULTS: The positive rates of cTnI and CK-MB in the myocarditis group were 89.5% and 60.5%, which were significantly higher than those in the nonmyocarditis group (8.3% and 29.2% respectively) and healthy control group (0) (P<0.05). 82.4% of positive cTnI occurred within one week of the onset. There were no differences in the positive rates of cTnI and CK-MB between the CVB1-6 IgM positive group and the negative one. CONCLUSIONS: The sensitivity and specificity of cTnI in the diagnosis of myocardial injury are superior to the CK-MB test and the diagnostic window of cTnI may be wider. cTnI appears to be an excellent new clinical marker for the diagnosis and the evaluation of prognosis of myocarditis.