Methods: Twenty-seven patients with acute first-time reperfused MI were studied. Infarct size was determined by delayed contrast-enhanced magnetic resonance imaging (DE-MRI) and estimated with the 50-criteria/31-point Selvester QRS scoring system 1 week after admission. The findings in the present study were compared with previous postmortem studies exploring the quantitative relationship between Selvester QRS score and MI size in nonreperfused patients. Results: The quantitative relationship between QRS score and MI size by DE-MRI in the present study of early reperfused MI was significantly different from previous postmortem histopathology studies of nonreperfused MI (P < 0.0001). In the present study, each QRS point represented approximately 2% of the left ventricle, compared to approximately 3% in previous postmortem histopathology studies of nonreperfused MI. When only considering small to moderate MI sizes, there was no significant difference in the quantitative relationship between QRS score and infarct size (P > 0.05). Conclusions: There is a different quantitative relationship between QRS score and MI size in early reperfused MI compared to nonreperfused MI, partly explained by differences in MI size. Thus, the Selvester QRS scoring system may not be linearly related to MI size. Ann Noninvasive Electrocardiol 2010;15(3):238-244.