(EDs) to prioritize patients based on the severity of their conditions. In the context of suspected acute coronary syndrome (ACS), accurate triage is crucial for timely intervention and optimal patient' outcomes. Aim: To evaluate the accuracy of the ESI triage score in predicting cardiac events among suspected ACS patients in the ED. Design and Methods: A prospective correlational observational study design was performed in cardiac ED. Tools Three tools were utilized to collect data pertinent to the study: Tool l: Patients' assessment (patients personal characteristics, vital signs) Tool II: ESI triage score sheet. Tool III: major adverse cardiac events (MACE) incidence among studied patients within 30 days. Results: Patients were triaged as (42.5%) ESI score 1, (41.0%) as ESI score 2 and (16.5%) as ESI score 3. ESI score ≤ 1 had sensitivity and specificity, positive, negative predictive value, and area under the curve of 53.52% and 84.48%, 89.4%, 42.6%, and 0.704, respectively. Conclusion: This study concludes that the ESI triage scores have a moderate accuracy in predicting cardiac events among suspected ACS patients at the cardiac ED. The study recommended: That enhanced training and possibly integrating additional diagnostic tools or biomarkers to improve the ESI score's sensitivity and overall predictive accuracy. Reapply this research on a large sample size acquired from different geographical areas in Egypt.