OBJECTIVE: To evaluate the diagnostic value of serum cardiac troponin Ⅰ (CTn Ⅰ) in the neonatal meconium aspiration syndrome (MAS) with myocardial lesions. METHODS: Serum CTn Ⅰ and CK MB levels were determined by the chemiluminoimmunoassay and enzyme assay in 65 neonates of MAS with or without myocardial lesions (n=35 and n=30, respectively) and 15 normal newborns. RESULTS: The serum CTn Ⅰ level in the neonates of MAS with myocardial lesions [( 0.67 ± 0.13 ) ng/ml] was much higher than that in those without myocardial lesions [( 0.07 ± 0.05 ) ng/ml] and normal neonates [( 0.07 ± 0.03 ) ng/ml] on day 2～3 of life (P< 0.05 ). CONCLUSIONS: CTn Ⅰ appears to be one of the specific markers for the diagnosis of MAS with myocardial lesions in neonates.