Backgrounds: Cardiac magnetic resonance imaging (CMRI) can be used to identify myocardial morphological changes such as infarct size, microvascular obstruction (MVO), and myocardial hemorrhage (MH), as well as functional parameters after acute myocardial infarction (AMI). We therefore investigated the correlation of infarct-related clinical finding after ST-segment-elevation AMI. Methods: Seventy-six patients with ST-elevation AMI treated with primary percutaneous intervention were analyzed. After successful procedure, CMRI was studied within the first week. T2-weighted CMRI was used to identify MH, whereas MVO and infarct size were determined on contrast-delayed image, and left ventricular function obtained using cine image. Results: Twenty-one (28%) and 18 patients (24%) presented with MH and MVO. The infarct size was associated with ejection fraction on echocardiography (r=-0.45, p=0.001), peak troponin-I level (r=0.66, p<0.001), peak creatinine-kinase (CK) -MB level (r=0.68, p<0.001), and degree of ST-segment-elevation resolution (r=-0.29, p=o.015). Multiple regression analysis showed that infarct size was only related to peak CK-MB level (beta=0.48, p=0.001). MH and MVO were associated with peak CK-MB level (odd ratio=1.01, p<0.001, and odd ratio=1.01, p=0.003, respectively) and peak troponin-I level (odd ratio=1.16, p=0.003, and odd ratio=1.01, p=0.004, respectively). Multivariate analysis showed peak CK-MB level to be an independent predictor of MH and MVO. Conclusion: peak CK-MB level can significantly be correlated with morphological change of myocardium on CMRI in patients with reperfused ST-segment-elevation AMI.