Ventilator associated pneumonia (VAP) is associated with morbidity, mortality and prolonged hospitalization and represent a serious threat to child safety. This study aimed to evaluate the effect of preventive bundle guidelines on nurses' knowledge and compliance towards ventilator associated pneumonia in pediatric critical care units. This study was carried out in pediatric, neonatal intensive care units and surgical care units at Benha Specialized Pediatric Hospital. A convenience sample of all the available nurses and mechanically ventilated children throughout pre and post assessment. Data were collected by using tool I: a structured interview quesrionnaire sheet (concerned with characteristics and knowledge of the studied nurses), tool II: The VAP bundle compliance checklist for assessing critical care nurses' compliance towards ventilator associated pneumonia preventive bundle guidelines and tool III: The child observational sheet: (that included characteristics of the mechanically ventilated children and the clinical pulmonary infection score (CPIS) for measuring incidence of (VAP). Results: The study results revealed that, in post intervention, the most of nurses had a good knowledge level and almost half of nurses had a satisfactory compliance level. There was a highly statistical significant difference between nurses' total knowledge and compliance level in pre/ post program intervention. There was a positive correlation between total nurses’ knowledge and compliance score in pre and post intervention .Conclusion: The study concluded that, nurses gained knowledge after implementation of preventive bundle guidelines. Recommendations: The study recommended that, Ventilator bundle guidelines for management of children under mechanical ventilation should be revised and available in pediatric critical care units in both Arabic and English language.