Background & Aim: The ventilator associated pneumonia is a common problem in critical care units. It is associated with increased mortality, cost and length of stay. Nurses have great role in preventing the ventilator associated pneumonia. The aim of this study was to assess nurses' performance in prevention of ventilator associated pneumonia .

  Methods & Materials: In this descriptive study, 110 nurses working in selected hospitals affiliated to Tehran University of Medical Sciences were selected using convenience sampling method. A 32-item observational checklist was provided based on the ventilator associated pneumonia prevention guideline. The nurses' performance was observed three times. Data were analyzed using descriptive statistics in the SPSS-16 . 

  Results: This study showed that the mean score of the nurses' prevention was 46.8±5.79. Most of the nurses (66.4%) had poor performance and 36.6% had relatively good performance. There were no nurses with favorable performance in the prevention of ventilator associated pneumonia. The highest score was in contact precaution (72±9.67) and the lowest score was in mouth hygiene (18.78 ± 17.4) .

  Conclusion: The majority of nurses had poor performance in prevention of ventilator associated pneumonia. More attention should be paid for planning appropriate training programs for nurses and giving adequate facilities to improve health care quality .