Background: Emergency department (ED) nurses are responsible for administering life support and rescuing care for individuals who are immobilized. Aim: To evaluate the effect of educational program on competence of emergency nurses' performance regarding sudden death of patients. Design: A quasi-experimental research design with a single group pre- and post-test was used. Setting: Assiut University Hospital which included four emergency units (general emergency unit, cardiothoracic emergency unit, medical emergency unit and trauma emergency unit). Subjects: Convenient sample of 60 available nurses. Tool one: Nurses' knowledge assessment questionnaire: To evaluate emergency department nurses' level of understanding regarding unexpected death. Tool two: Nurses practice observational checklist: Consisted of 24 elements in 50 phases, covered various aspects of cardio version and defibrillation operations. Results: The nurses' total knowledge score pre-intervention was 19.03 ± 15.701 which significantly increased to 54.53 ± 12.197 points after program implementation, and to 65.15 ± 8.851 points after 3 months of the program implementation (p < 0.001). The total score of nurses' performance before the program was 44.9 ± 37.39 points, which increased to 132.33 ± 29.88 after the program implementation. After 3 months of intervention, the total practice score was 158 ± 21.95 points with a highly statistically significant difference (p < 0.001). There was a statistically significant variance (p < 0.001) and a strong positive correlation (r=0.99) between the overall practice and knowledge scores. Conclusion: The effect of educational program on competence of emergency nurses' performance improved emergency nurses' judgments of appropriate behavioral responses when encountering sudden death, according to the study's results, which raises the caliber of their job. Recommendations: Further studies are required to determine whether enrolling emergency nurses in death education programs can considerably enhance their sense of appropriate behavioral reactions while handling unexpected death.