Serum cTnT, CK-MB and LDI were measured in 30 patients with AMI, 76 patients with VMC, 12 patients who had undergone operation without cardioplegia, 16 patients who had received open heart operation, 15 patients who had undergone thoracotomy for non-heart surgery and 55 healthy people. Concentration of serum cTnT was 0.057±0.056 μg/L in healthy people,0.069±0.032 μg/L in patients who underwent thoracotomy for non-heart surgery, 0.328±0.472μg/L in patients with VMC, 0.388±0.279 μg/L in patients with DCM, 4.259±4.619 μg/L in patients with AMI, 8.55±6.78 μg/L in patients who had undergone operation without cardioplegia and 16.03±6.01 μg/L in heart operation patients. In patients with VCM and DCM, serum cTnT was more specific and sensitive than CK-MB and LDI for diagnosing myocardial injury. In patients with AMI and heart operation patients, the increasing multiple of serum cTnT was obviously higher than that of CK-MB and LDI. 72 h after heart operation, cTnT was still higher than normal, while CK-MB had reted to normal level. Serum cTnT had higher specificity and sensitivity and longer diagnostic period in diagnosing myocardial injury. Moreover, cTnT assay could indicate the degree of myocardial injury. So, quantitative analysis of cTnT can be used as a routine examination in the diagnosis of myocardial injury.