Background: A global public health problem is poisoning. Also consider one of the most important reasons for attendance in emergency unit. The critical care nurses play an essential role in assessing poisoning patient at emergency unit. Patients with poisoning have a better chance of surviving if they are identified early and treated effectively.  Aim: This study aimed to assess knowledge and practices of critical care nurses about toxicological emergencies. Subjects and method:  Study Design: A descriptive design was utilized in this research.  Setting: This study was carried out at poisoning center in Al-Mansura city, emergency department in Al-Manzala central hospital and El-Salam hospital. Subjects:  A convenient sample of 81 nurses included in the study. Tools: Two tools used for data collection, nurses' knowledge questionnaire and nurses' practice observational checklist. Results: More than half (54.3%) of participants had poor knowledge; however (76.5%) of them had acceptable practices about toxicological emergencies. There was a positive statistical significant correlation between overall nurses' knowledge and practices about toxicological emergencies as p value is 0.002. Conclusion: This study concluded that 54.3% of participants had overall poor knowledge and 76.5% of them had acceptable practices about toxicological emergencies. There was a positive statistical significant correlation between overall nurses' knowledge and practices about toxicological emergencies. Recommendation: Educational training programs for nurses regarding toxicological emergencies are recommended.