Background and objective: Q waves on a 12-lead electrocardiogram (ECG) are considered a classic hallmark of prior myocardial infarction. However, Q waves may regress and disappear with time especially in patients treated with reperfusion therapy despite there being continued evidence of myocardial scarring. A prior study has suggested that the fragmented QRS complex on an ECG is a highly sensitive and specific marker of myocardial scar on a nuclear stress test. We investigated the association of the fragmented QRS complex versus the Q wave with myocardial scar detected by delayed contrast enhanced cardiovascular magnetic resonance (DE-CMR) imaging in patients with myocardial infarction. Methods: ECGs of 130 subjects with myocardial infarction who underwent a DE-CMR were analyzed. Myocardial infarctions were labeled transmural if hyperenhancement extended throughout the entire LV wall at any point. We used the Q wave definition from the Thrombolysis In Myocardial Infarction (TIMI) group in the primary analysis which defines QW MI as pathologic QW (>30 ms) in >2 contiguous leads Result: The final diagnosis was non-ST segment elevation myocardial infarction in 38 (29.2%) and ST segment elevation myocardial infarction in 92 (70.8%) patients. Delayed enhancement was observed in 121 (93.1%) patients. Transmural enhancement was noticed in 52 (43.0%) and subendocardial in 69 (57%) patients. The sensitivity and specificity of the Q wave and fQRS for diagnosing delayed enhancement were 58.7% vs. 91.1% and 88.9% vs. 33.3%. The areas under the ROC curves (AUC) for diagnosis of delayed enhancement were 0.738 (95% confidence interval, 0.60 to 0.88, p=0.02) for the Q wave and 0.52 (95% confidence interval, 0.32 to 0.72, p=0.83) for the fQRS. The AUC for diagnosis of transmural enhancement were 0.58 for Q wave and 0.48 for fQRS. Conclusion: The fQRS has a higher sensitivity than the Q wave but lower specificity for detection of delayed enhancement. The fQRS is not superior for the diagnosis of myocardial scar or its transmurality than Q wave.