We measured the incidences of protein and fat depletions and the frequencies of acute and chronic protein-energy malnutrition during stress states in children and investigated the influence of early enteral feeding on nutrition indices and acute-phase proteins. Seventy-one, consecutively enrolled, critically ill children received early enteral feeding (energy intakes equal to 0.50, 1, 1.25, 1.5, and 1.5 of the predicted basal metabolic rates on days 1 through 5, respectively) through nasogastric tubes. On the first day of the study, 16.7% of the patients already were depleted of protein and 31% of fat stores. Overall, 16.9% were at risk for chronic protein-energy malnutrition and 21.1% for acute protein-energy malnutrition, whereas 4.2% and 5.6% already had chronic and acute, respectively protein-energy malnutrition. Only 22.7% of patients without protein deficiencies versus 37% of those at risk or already deficient developed multiple-organ system failure. Transferrin and prealbumin levels improved at the end of the period of early enteral feeding (187 +/- 6.6 versus 233 +/- 7 mg/dL, P < 0.0001; 15.1 +/- 2 versus 21.9 +/- 2.9 mg/dL, P < 0.0001; respectively); survivors had higher prealbumin levels than non-survivors (22.3 versus 15.5 mg/dL). With logistic regression analysis, only repleted energy, not anthropometric or nutrition indices, was independently associated with survival (P = 0.05). These results reinforce the observation that critically ill children are at risk for fat or protein depletion and development of malnutrition, which is associated with increased morbidity and mortality. We conclude that early enteral nutrition improves nutrition indices and outcomes.