Background: Emergency nurse play one of the most critical roles in a health care setting, nurse is the frontline of triage and treatment for patients with everything from mild colds to extreme injuries. Nurses have the unique opportunity to reduce the potential for acquired infections. Utilizing the skills and knowledge of nursing practice, can facilitate patient recovery while minimizing complications related to infections the aim: the aim of this study is to evaluate nurses' performance and barriers to use infection control standard precautions in emergency unit Design: A Descriptive analytical research design setting: the study was conducted in emergency unit at Ain Shams University specialized hospital, Cairo Governorate, Sampling: A convenience sample, all nurses was taken, the total number (80) of nurses. (65 diploma nurses and 15 bachelor nurses) working in emergency unit. Tools: two tools were used in this study for data collection, First: an interviewing questionnaire divided into three parts: Part 1 nurses socio- demographic, Part 2 Nurses knowledge& Part 3 the barriers hindering the application of infection control standard precaution .Second: Observation checklist for assessing nursing performance regarding infection control standard precautions. Results: Reveals that 46.1% had correct knowledge about infection control, while77.5 had incorrect performance with infection control standard precaution. Also reveal that barriers related to nurses with mean47.5& barriers related to the facility with mean32.92.Conclusion: Nurse's current performance to use infection control standard precaution in emergency unit lack of nurse's knowledge and performance toward infection control standard precautions in emergency unit, and highly perceived barriers to use infection control standard precautions. Recommendations: the study recommended that Continuing training for nurses to demonstrate their compliance/ performance/ utilization of standard precautions of infection