Large infarcts are associated with a terminal QRS-distortion in ST-elevation myocardial infarction (STEMI) patients. Late gadolinium enhancement (LGE) on the cardiac MRI (CMR) can depict an infarct distribution. However, less is known about the relationship between the LGE findings and QRS-distortion on admission, including the best ECG-lead location to reveal the QRS-distortion (DIS-lead) in STEMI patients. Fifty STEMI patients successfully treated with percutaneous coronary intervention were classified into two groups according to whether the QRS-distortion was positive (+) or negative (-). The LGE on a recent CMR was classified into 12 left ventricular segments (Basal-Middle-Apical × Anterior-Septal-Inferior-Lateral). The coincidences between the segmental LGE scores and DIS-lead were investigated. All patients were divided into 23 QRS-distortion (+) and 27 QRS-distortion (-) groups. The total LGE score was significantly greater in the QRS-distortion (+) group (14.7 ± 6.8 versus 9.6 ± 6.2, P < 0.01). The highest LGE score in 96% of QRS-distortion (+) patients was 4, and a score 4 segment indicated a good selection of the DIS-lead (86.4%). QRS-distortion in the ECG on admission represents severe transmural infarction in the LGE using CMR, which represents large infarcts in STEMI patients.