Background: Pediatric emergency department nursing is one of the most challenging areas of nursing care where caring for pediatric patients in intensive care environments requires advanced training and experience and good preparedness because the clinical picture for critically ill children can change rapidly. Aim of this study: was to assess the preparedness of nursing staff during critical situations at pediatric emergency units. Design: A descriptive design was followed to achieve the aim of this study. Setting: The study was conducted at Pediatric Emergency Units at children hospital affiliated to Ain Shams University Hospitals and Al-Matarya educational Hospital. Sample: A convenient sample composed of 50 nurses working at the previously mentioned settings. Tools of data collection: Pre- designed questionnaire sheet to assess knowledge, nurse's Attitude Likert Scale to assess attitude and observational checklists to assess practice of nursing staff. Results: The results of this study showed that, more than half of the studied nurses had unsatisfactory knowledge, negative attitude and incompetent practice regarding preparedness during critical situations at pediatric emergency. Furthermore, there was a statistical significant correlation between total studied nurses' knowledge, total attitude and total practice. Conclusion: More than half of the studied nurses had unsatisfactory level of knowledge, negative attitude and incompetent practice regarding pediatric emergency preparedness during critical situations. Moreover, there was statistically significant correlation between studied nurses' total knowledge, attitude and practice. In addition, there was statistically significant correlation between studied nurses' total knowledge, attitude, practice and their demographic characteristics. Recommendations: The study recommended the importance of implementing an educational training program to improve nurses' performance regarding preparedness during critical situations at pediatric emergency units.