Background: Nutrition is a basic human need that changes throughout the life cycle and along the wellness- illness continuum. Most intensive care patients cannot eat orally for various reasons, as been intubated to mechanical ventilation, under sedation, or have alteration in their level of consciousness. For these patients, enteral feeding is the preferred method of nutritional support. In particular, early enteral feeding has been shown to decrease the rates of infection, length of hospital stay, and medical costs among ICU patients. Aim: to assess nurses' performance in providing nutritional support for mechanically ventilated patients in Al-Azhar university hospital, Damietta General Hospital and Rass El bar central Hospital. Subject and Methods: descriptive research design carried out in 60 nurses, working at intensive care units, 30 nurses intensive care unit at Al-Azhar university hospital, 20 nurses at Damietta General Hospital and 10 nurses at Rass El bar central hospital and given care for 60 mechanically ventilated patients in these hospitals. The toolsfor data collections included questionnaire sheetand observational checklist. results: show most of studied nurses had satisfactory level of knowledge and mostof them had unsatisfactory level of practice regarding nutritional support for mechanically ventilated patients; there is no statistically significant relation or correlation between studied nurse's demographic characteristics and their total score of knowledge or total score of practice.Conclusion: The study concluded that all nurses need to improve their performance during providing nutrition for mechanically ventilated patients.Recommended: The study recommended that improved nursestheoretical knowledge, clinical applications of providing nutrition for mechanically ventilated patients and continuous evaluation of nurse's knowledge and practice are essential to identify nurses needs and design heath teaching programs according their needs.