OBJECTIVE: To evaluate dynamic changes in serum cardiac troponin I (CTnI) levels and myocardial enzyme activities following asphyxia in newborns.METHODS: Serum CTnI levels, and creatine dinase (CK), creatine kinase MB isoenzyme (CK MB), lactic dehydrogenase (LDH) and aspartate aminotransferase (AST) activities were measured by the automatic chemoluminescence and biochemical assay at 0, 6, 12, 24, 72 hr and 10 days in 26asphyxiated newborns ( 16 with mild asphyxia and 10 with severe asphyxia) and in 10 non asphyxiated neonates.RESULTS: Serum CTnI levels, and CK, CK MB, and LDH activities in both mild and severe asphyxia infants were significantly higher than those in the controls (P< 0.01 ). In the asphyxiated infants, the peak values of CK and AST occurred at 6 hr, of CTnI and LDH at 12 hr, and of CK MB at 12～24 hr of life. The levels declined gradually after treatment. CONCLUSIONS: Determination of serum levels of CTnI and CK, CK MB, LDH, and AST activities are helpful in making an earlier diagnosis and in planning effective treatment for myocardial damage following asphyxia in newborns.