BACKGROUND AND OBJECTIVES: Increased QT dispersion (QTD) in patients with acute myocardial infarction (AMI) may be related with such adverse events as sudden cardiac death and ischemic heart failure. SUBJECTS AND METHODS: Two hundred eight patients (age : 62+/-10.4 years, 158 males), underwent diagnostic coronary angiography under the diagnosis of AMI between January and December 2001 at the Heart Center of Chonnam National University Hospital, and these patients were enrolled to evaluate the relationship between the QTD and myocardial injury and the complex coronary arterial lesion. RESULTS: A QTD of over 80 ms was observed in 89 patients (42.7%). There were in 61 patients with ST elevation myocardial infarction (STEMI, 68.5%) and 28 patients with non-ST elevation myocardial infarction (NSTEMI, 31.5%). There was no correlation between the QTD and such risk factors as hypertension, diabetes, gender, smoking, hyperlipidemia and family history. The level of CK-MB on admission was correlated with the QTD (112.5+/-98.1 U/L in the group with a QTD over 80 ms and 72.6+/-73.4 U/L in the group with a QTD under 80 ms, p<0.05). The ejection fraction measured by two dimensional echocardiography on admission showed correlation with the QTD (50.9+/-11.4% in the group with a QTD over 80 ms and 54.7+/-11.2% U/L in the group with a QTD under 80 ms, p<0.05). For the coronary angiographic findings, the lesion type, according to American College of Cardiology/American Heart Association classification, correlated with the QT dispersion (type B2 or C : 64.1% in the group with a QTD over 80 ms, 49.6% in the group with a QTD under 80 ms, p<0.05) CONCLUSION: There was significant correlation between the prolonged QTD and the severity of myocardial injury at admission, and the complex coronary arterial lesion in patients with AMI.