Malnutrition and gastrointestinal complications are considered important causes of increased mortality, morbidity and prolonged duration of stay in the postoperative pediatric cardiac surgery ICU.A structured detailed follow up sheet was prepared and applied on 100 patients in the ICU who are subjected to the routine nutritional support carried out in the unit to study the effect of malnutrition and gastrointestinal complications on the different body systems of these patients.A structured protocol for nutrition was prepared (based on the most recent updated international guidelines E.S.P.E.N 2007 and A.S.P.E.N 2009) and applied on 30 patients inside the postoperative pediatric cardiac surgery ICU to select the most appropriate way of feeding whether oral, Nasogastric or parenteral and also to study the effect of the delivered nutrition on the mortality and morbidity of these patients (clinically and laboratory).Our study concluded that the nutritional and other clinical outcomes including gastrointestinal complications as well as fate of the patients was markedly improved after application of the evidence based protocol of nutrition based on the most recent updated international guidelines for nutrition (A.S.P.E.N 2009 and E.S.P.E.N 2007).From our results, we recommend that nutrition delivered to the patients in the ICU should be guided by an evidence based nutritional protocol and that the regular assessment of the nutritional status of the patients clinically (weight, height, triceps skin fold) and laboratory (BUN, calcium, phosphorous, albumin).