Nutritional support of critically ill infants and children has a major impact on the morbidity and ultimate survival of these patients. Parenteral nutrition has undergone many changes since its original use more than 20 years ago. This article summarizes some of the more recent modifications in parenteral nutrition. The use of insulin to control hyperglycemia associated with parenteral nutrition is controversial, although many advocate its use as a means to optimize caloric intake in the very low-birthweight infant for whom this is often a significant problem. The advantages of using a 20% lipid emulsion, as opposed to a 10% emulsion, are emphasized. Supplementation with carnitine and selenium is controversial, and studies endorsing and opposing their use are described.