Myocardial infarction is the prototype of a real emergency, both efficacy and speed are necessary for effective management, it occurs as a result of pathological event in the setting of coronary artery with the marked cardiac insult and injury. there is a golden hour between life and death. it needed to be taken care of within the 1-hour time frame. The aim of this study was to assess nurses’ performance during golden hour of myocardial infarction in emergency department and cardiac catheterization unit. Design: A descriptive exploratory design was utilized to achieve the aim of the study. Setting: the study was conducted at emergency department and cardiac catheterization unit at Al-Fayoum University hospital. Sample: A convenient sample of 60 nurses were included in the study. Tools: Tool I: Self-administered interview questionnaire: included two parts. Part I: demographic characteristics of nurses, Part II: Nurses’ knowledge regarding golden hour during myocardial infarction. Tool II: Observational checklist of nurses’ practices regarding care of patients during golden hour of myocardial infarction Results: the study findings showed that 36.7% of studied nurses had satisfactory total knowledge scores regarding definition of MI compared to 80% of them had unsatisfactory total knowledge scores regarding medical treatment of MI. also30% of the studied nurses had competent scores of practices during and immediate post intervention compared to 85% of them had incompetent scores of practices regarding activation of cardiac catheterization lab team. Conclusion: the majority of the studied nurses had unsatisfactory total level of knowledge regarding golden hour of myocardial infarction and most of them had incompetent total level of practices regarding care of patients during golden hour of myocardial infarction. Recommendations: continuous educational programs should be planned on regular basis to emergency nurses for enhancing their knowledge and practice to achieve high quality of care.