Background: Triage is an essential function of staff in the emergency department. Nurses ‘knowledge about triage is decision making, and effective decision-making can influence the health outcomes of patients. Which they play a key role in triage application should be sufficiently prepared to enhance the triage nurse will be adequate perception and positive satisfaction regarding triage application in the emergency department. Aim: Assess perception and satisfaction of nursing staff regarding triage application in the emergency department. Design: A descriptive research design was used. Setting: This study was carried out at Emergency Department at the Emergency and Reception Hospital of Cairo University, Egypt. Sample: A convenient sample of 80 nurses. Tool: One tool was used to collect study Demographic data: Nurses Knowledge, Practices, Perception, and Satisfaction through self-administrated interview questionnaire. Results: Results of the present study showed that 58.8% of the studied nurses had satisfactory level of knowledge, 61.3% of studied nurses had adequate level of total perception, 63.8% of studied nurses had adequate level of total practices, and 63.8% of studied nurses had positive satisfaction level about triage application in the emergency department. Conclusion: there was a positive strong highly statistically significant correlation between knowledge, practice perception, and satisfaction level regarding triage application in the emergency department among the studied nurses. Recommendations: Providing in-service educational training programs based on nurses' needs to improve their knowledge and practice related to triage application in the emergency department in both Arabic and English languages.