Background: Ventilator-associated pneumonia (VAP) is a lung infection that develops in a person who is on a ventilator for 48 hours or longer. results from the invasion of the lower respiratory tract and lung parenchyma by microorganisms. Aim of the study: To investigate the nurses role among ventilator associated pneumonia and evaluate the nurses s knowledge and practice to prevent Ventilator-associated pneumonia.Subject and Methods:Researsh design: Descriptive exploratory study was used to carry out this study Subject: 50nurses of different categories working in the emergency ICU during the period of study Setting:the study was conducted in emergency ICU at Zagazig University Hospital, Egypt.Tool of Data collection: Three tools were used; an interview questionnaire sheet was developed by the researcher in Arabic language. Nurses' knowledge of evidence-based guidelines for the prevention of VAP, multiple choice questionnaire and observational checklist for nurses' performance for VAP prevention. Results: Generally high percentages of nurses in the study sample having satisfactory knowledge about VAP.this exceeded three-fourth of the sample in all areas of knowledge. The only exceptions were related to treatment of VAP (48.0%) and the nurse’s role in prevention VAP during intubation (70.0%). Conclusions: The study findings conduce to the conclusion that a large proportion of the nurses in the study settings have satisfactory knowledge of Ventilator Associated pneumonia (VAP). Recommendations:The study recommends theoretical training to improve nurses’ knowledge of VAP and of their role in its prevention.