INTRODUCTION The myocardium at risk (MaR) represents the quantitative ischemic area destined to myocardial infarction (MI) if no reperfusion therapy is initiated. Different ECG scores for MaR have been developed, but there is no consensus as to which should be preferred. OBJECTIVE Comparisons of ECG scores and Cardiac Magnetic Resonance (CMR) for determining MaR. METHODS MaR was determined by 3 different ECG scores, and by CMR in ST-segment elevation MI (STEMI) patients from the MITOCARE cardioprotection trial. The Aldrich score (AL) is based on the number of leads with ST-elevation for anterior MI and the sum of ST-segment elevation for inferior MI on the admission ECG. The van Hellemond score (VH) considers both the ischemic and infarcted component of the MaR by adding the AL and the QRS score, which is an estimate of final infarct size. The Hasche score is based on the maximal possible infarct size determined from the QRS score on the baseline ECG. RESULTS Ninety-eight patients (85% male, mean age 61years) met STEMI criteria on their admission ECG and underwent CMR within 3-5days after STEMI. Mean MaR by CMR was 41.2±10.2 and 30.3±7.2 for anterior and inferior infarcts, respectively. For both anterior and inferior infarcts the Aldrich (18.2±5.1 and 18.6±6.0) and Hasche (25.3±9.8 and 26.4±8.8) scores significantly underestimated MaR compared to MaR measured by CMR. In contrast, MaR by the van Hellemond score (37.0±14.2 and 31.7±12.8) was comparable to CMR. CONCLUSION We tested the performance of the electrocardiographic estimation of myocardium area at risk by Aldrich, Hasche and van Hellemond ECG scores in comparison to MaR measured by CMR in STEMI patients. MaR by the van Hellemond score and CMR were comparable, while Aldrich and Hasche underestimated MaR.