Introduction: Despite technological advances, malnutrition is still widespread in pediatric intensive care units (PICUs). Studies have shown that 24% to 55% of patients present with acute or chronic malnutrition on admission and that deterioration of nutrition status commonly occur during hospitalization. Critically ill children have a high risk of malnutrition because of stress-induced changes in intermediary metabolism; these changes are characterized by an increased basal metabolic rate and intensive protein catabolism. Nutrition care studies have proposed that an early intervention that targets nutrition assessment can prevent or minimize the complications ofmalnutrition. Nutrition therapy (NT) is indicated when a patient is unable to receive calories and nutrients orally for a long period of time. Enteral nutrition (EN) is preferred because it is more physiologic, promotes intestinal trophism, stimulates the immune system, and reduces the incidence of bacterial translocation and sepsis. In addition, it presents fewer complications and costs less than parenteral nutrition (PN). However, when it is impossible to use the digestive tract, PN is the only alternative for ensuring an adequate supply of nutrients during hospitalization. Methods: The present study is a prospective cohort study in which 60 patients need the mechanical ventilation in PICU ward of Mofid Children s Hospital on 2018. The goals of the project provided to parents of patients and written consent obtained. Estimates of energy requirements will becalculated based on basal metabolism (BMR) or resting energy consumption (REE), growth rate, physical activity, and stress factors. Estimates of energy requirements were based on the Schofiel Prediction Criterion for BMR as well as the American Association of Prenatal and Parenteral Nutrition (ASPEN) for children admitted to PICU. In this study, moderate and severe malnutrition were considered as malnutrition. Patients were randomly assigned to early enteral or late enteral nutrition therapies according to disease conditions, patient’s indications and PICU’s fellowship view. 30 patients will be evaluated in each group. Patients undergoing Early Enteral should be treated withFormula High Calorie valves during 48 hours after admission to the PICU according to the guidelines for initiation and progression of continuous bolus and EN. Also, 30 patients will be treated according to the PICU protocol by Late enteral. Results: Patients in both groups were similar in demographic and anthropometric data and prevalence of malnutrition at baseline. Early enteral nutrition was associated with a significantly lower incidence of infections, reduced length of hospital stay, intubation time and PRISM score, mortality in hospital and increased of serum Albumin and IGF-1 in patients (P<0.05). Early enteral nutrition improved or maintained the anthropometric status of the atients and reduced malnutrition. Conclusions: The results of this study support the benefit of the early initiation of enteral nutrition.