We investigated clinical implications of serum tenascin-C (TN-C) levels in patients with acute myocardial infarction (AMI) treated with thrombolytic therapy Serum TN-C levels were measured by ELISA in 60 cases presented with acute STEMI and 20 normal controls. The mean serum TN-C level of AMI patients on admission (57.5 ng/ml) was significantly higher than that of controls (57.49 ± 19.89 ng/ml vs. 34 ± 3.02 ng/ml; p=0.0001), follow-up examination (mean: 6 months) revealed that 17 of 60 AMI (28%) patients showed left ventricular (LV) remodeling (20% enddiastolic volume increase), and in 6 (10%), major adverse cardiac events (MACE) were detected. By receiveroperating characteristic (ROC) analysis, TN-C levels clearly discriminated prediction of LV remodeling and MACE compared with other variables including creatine kinase-MB, and LV function. Diabetes and TN-C were correlated with MACE in our study. The findings suggest that serum TN-C levels might be useful in predicting LV remodeling and prognosis after AMI.