Nutritional support of the critically ill or postoperative pediatric patient continues to develop as a clinical science in the face of technologic, pharmacologic, and nutritional science advances. For ethical and logistical reasons, however, clinical trials of new technologies and interventions often are performed first in adult subjects, and the pediatric intensivist and nutritionist are thereby left to draw conclusions from this literature. This review summarizes recent developments in the clinical nutrition literature concerning the nutritional care of intensive care unit patients, emphasizing experience with pediatric patients when possible. The central role of estimating energy requirements in the intensive care unit, the development of enteral formulas with nutritional as well as possible immunologic properties, the use of anabolic hormones to attenuate the catabolic response to illness, the concept of "conditionally essential" amino acids, and the propensity to use the parenteral route of nutrition when the enteral route is still available are discussed. Future directions in nutritional support, including the development of nutritional pharmacotherapy, are also considered.