Background: Patients with successful reperfusion and preserved left ventricular ejection fraction (LVEF) after ST‐segment myocardial infarction (STEMI)have always been thought to have low risk for adverse events. Great interest is focused on finding simple, noninvasive tools to refine risk stratification among them. Objectives: We hypothesized that degree of ST‐segment resolution (STR) after STEMI can identify high‐risk group among patients with LVEF ≥ 50% following STEMI. Methods: During the period from January to July 2017, patients with successful rep‐ erfusion of STEMI and LVEF ≥ 50% were prospectively included. Patients were di‐ vided into two groups based on the percent of ST segment resolution using single lead STR method; group I (complete STR ≥ 70%) and group II (partial STR 50%–70%). The endpoint was a composite of cardiovascular mortality, re‐hospitalization for heart failure and urgent revascularization at 30‐day. Results: After exclusion, 110 patients were left for final analysis. No significant dif‐ ferences in all baseline characteristics were found between both groups. The primary endpoint occurred in seven patients (12.7%) of group I versus 17 patients (30.9%) of group II (Relative risk = 2.43, 95%CI = 1.1–5.4, p = 0.021) driven by a significant re‐ duction in rates of re‐hospitalization due to heart failure. A multivariate logistic re‐ gression analysis showed incomplete STR to be a significant independent predictor for 30‐dayMACEs (OR 3.25, 95% CI1.2–8.83, p = 0.02) even after adjustment for lo‐ cation of infarction. Conclusion: Complete STR predicts 30‐day outcome in patients with preserved LVEF following successful reperfusion of STEMI.