Purpose Carnitine is a carrier molecule transporting long-chain fatty acids (LCFAs) into the mitochondria for fatty acid β-oxidation. The purpose of this study is to evaluate the role of carnitine supplementation in parenteral nutrition (PN) within the pediatric population. Our goal was to determine a weight range for which empiric carnitine supplementation is justified and to determine a weight range at which a carnitine level should first be drawn to confirm a deficiency prior to supplementation. Secondarily, we tried to determine a relationship among carnitine deficiency, hypoglycemia, and hypertriglyceridemia. Methods This was a retrospective observational study to evaluate 2 groups of pediatric patients (weighing 0.68 kg to 60 kg) who were NPO and receiving PN. The first group of patients ( n = 454) received carnitine supplementation (15 mg/kg/day) upon initiation of PN. The second group ( n = 299) did not receive carnitine supplementation until they were determined to have a carnitine deficiency. Results The data indicated that 82% of the patients weighing less than 5 kg were deficient. Patients weighing more than 5 kg had serum carnitine levels within the normal range. Therefore, patients receiving PN and weighing less than 5 kg should be supplemented with carnitine. Comparison of triglyceride, glucose, and carnitine showed no statistically significant difference ( P = .1936). Conclusion Patients weighing more than 5 kg should have serum carnitine levels drawn within 7 days to determine whether supplementation is needed. There is no statistical correlation among carnitine deficiency, hypoglycemia, and hypertriglyceridemia.