Pain is a significant problem for critically ill patients throughout their stay in the intensive care unit especially who are mechanically ventilated .Turning procedure is one of the most common procedure which may cause pain for critical ill patients :Aim: of this study is to assess pain during turning procedure for patient on mechanical ventilation. Research question: What is the characteristics of pain caused by turning procedure among patients on mechanical ventilation? descriptive research design was utilized. The sample: a convenient sample was used ;it consisted of 92 adult male and female on mechanical ventilation in intensive care unit at Benha university hospital , those above 65years, receiving neuromuscular blocking agents and with peripheral neuropathy were excluded . Tools of data collection 1): Data collection sheet (developed by the researcher): it includes part a: Sociodemographic and medical related data, part b: physiological parameters sheet 2): Critical care pain observation tool and 3): Facial pain scale. The duration of the study lasts for six months from (May 2015 to October 2015). The results revealed that there were 87% have severe pain during procedure ,while 4.3% had severe pain 10 minutes after the procedure. There was no statistical significant difference between level of pain for both male and female as well co morbid disease . There is highly statistical significant difference between behavior indicator and physiological parameters before, during and ten minute after turning procedure. Recommendations: Pain assessment should be a part of the overall management for mechanically ventilated patients and must be routinely documented in the patient’s record and nursing notes and regularly updated. Also the results highlight the need to administer additional analgesia before turning procedure, particularly in mechanically ventilated patients unable to self-report or with cognitive impairment.