Background: Speckle-tracking echocardiography has emerged as a unique technique for accurately evaluating myocardial function by analyzing the motion of speckles identified. Speckle-tracking measured under stress may offer an opportunity to improve the detection of dynamic regional abnormalities and myocardial viability. Objective: The aim of the current study was to evaluate stress speckle tracking to detect myocardial viability in comparison to cardiac MRI in post-STEMI patients. Patients and methods: 74 patients were prospectively enrolled in 18-month's study. Dobutamine stress echocardiography was performed 4 days post-infarction accompanied with automated functional imaging analysis of left ventricle during rest and then during low dose stress. All patients underwent a follow up stress echocardiography at 3 months with speckle tracking analysis. Cardiac MRI took place concomitantly at 4 days post-infarction and 3 months. Results: Investigating strain rate obtained with stress speckle tracking after revascularization predicted the extent of myocardial scar, determined by contrast-enhanced magnetic resonance imaging. A good correlation was found between the global strain and total infarct size (R 0.75, p< 0.001). Furthermore, a clear inverse relationship was found between the segmental strain and the transmural extent of infarction in each segment. Meanwhile it provided 81.82% sensitivity and 82.6% specificity to detect transmural from non-transmural infarction at a cut-off value of -10.15. Conclusion: Strain rate obtained from speckle tracking during stress is a novel method of detecting myocardial viability after STEMI. Moreover, it carries a promising role in post-myocardial infarction risk stratification with a reasonable prediction of reversible cardiac-related hospital re-admission.