Aim: This  study  aimed  to  evaluate  the effect    of enhancing   nurses `   competency  on   bundle  prevention  protocol  for  ventilator   associated   pneumonia (VAP).  Subjects  and  Method  : A quasi-experimental design was utilized for the  conduction  of this study   in the  following Critical   Care Units (Neuro- Medicine, Intensive Care Unit  (ICU) , Coronary  Care Unit (CCU)   and   Emergency)   of   Medical    Hospital   affiliated   to   Ain   Shams   University   and   El Sayed - Galal   Hospitals  .  Sample:  A purposive sample was composed of 70 critical care nurses and 40 critically ill patients from the above mentioned settings.  Tools of data collection : 1) Self-administered questionnaire  (pre / posttests) to assess the studied  nurses` knowledge  as  regards  Ventilator associated  pneumonia  (VAP) prevention  bundle . 2) An observation checklist (pre / posttests) to evaluate studied nurses ' practices in relation to  care  of  patients  with   Ventilator Associated  Pneumonia (VAP)  and bundle prevention  protocol . 3) Hamilton Anxiety Rating Scale (pre / posttests) to assess studied nurses` anxiety level. 4) Nurses` opinnionair sheet   (pretest) to identify their opinions regarding competency   obstacles. 5) Patients` condition assessment sheet (posttests).  Results: More than half   of the studied nurses had diploma nursing with less than five years of experience. In addition  , there were     unsatisfactory  level  of   nurses `  knowledge  , practices ,  added   to    elevated  anxiety  level  in    pretest   . As regards the studied patients,  less  than half   of  them had the age of  (20 - < 35 yrs).  Conclusion :   On  light of  the  current study  results , it   can  be   concluded that  , enhancing nurses' competency  (knowledge and practices)  through educational  guidelines  was helpful on adherence  to  bundle  prevention  protocol  for  ventilator associated pneumonia (VAP ). Recommendations: Further studies should be carried out on a large number of critical care  nurses  with        evidence   of    results  and    generalization  .