AbstractBackground: At the present time, the optimal timing anduse of enteral nutrition for mechanically ventilated medicalpatients is unknown. The current study will focus on the effectof early versus delayed enteral nutrition in critically illmechanically ventilated medical patients.Aim of Study: To compare between early versus delayedenteral feeding in Invasive Mechanical Ventilation (IMV)patients. To assess association linking early nutrition (<48hours after intubation), feeding route and calorie intake tomortality and risk of Ventilator Associated Pneumonia (VAP) in patient with Invasive Mechanical Ventilation (IMV).Patients and Methods: Patients will be scheduled toreceived their estimated total daily enteral nutritional require-ments on either day 1 (early-feeding group) or day 5 (late-feeding group) of mechanical ventilation. Patients in the late-feeding group will be also scheduled to receive 20% of theirestimated daily enteral nutritional requirements during thefirst 4 days of mechanical ventilation. Thirty (50%) consecutiveeligible patients will be entered into the early-feeding groupand thirty (50%) patients will be enrolled in the late-feedinggroup. All patients will be received enteral nutrition viacontinuous infusion by a feeding pump. Eligible patients will be followed in ICU for a maximum of 12 days or until death or discharge from ICU.Results: Logistic regression analysis shows that; afterapplying (forward method) and entering some predictorvariables; the increase in BMI and late feeding technique;had an independent effect on increasing the probability ofmortality occurrence; with significant statistical difference (p < 0.05 respectively). The increase in BMI and late feedingtechnique; had an independent effect on increasing the prob-ability of VAP occurrence; with significant statistical difference (p < 0.05 respectively). By using ROC-curve analysis, earlyenteral feeding predicted shortening of hospital stay, withfailed (64%) accuracy, sensitivity=63% and specificity=63% (p < 0.05).Conclusion: Evidence shows improvement in patientoutcomes associated with the use of EEN in a diverse popu-lation of critically ill patients. The results of our study strengthen our understanding of the benefits of EEN. These were evident even though <50% of the patients in each groupreached a goal rate of EN. Given the potential ease of consistentimplementation of EEN, the minimal cost associated withsuch a practice, and the potentially substantial.