Purpose: Preterm infants on parenteral nutrition are at a relatively high risk for hypertriglyceridemia because they have immature lipoprotein lipase activity. The purpose of this study was to analyze the clinical factors affecting lipid metabolism in preterm infants receiving parenteral nutrition and to evaluate the influence of intravenous heparin on serum triglycerides to determine the adequate heparin dose to prevent hypertriglyceridemia in preterm infants. Methods: A single-center retrospective review was conducted among preterm infants receiving parenteral nutrition between January 2006 and February 2011. In 75 patients, 110 determinations were performed within 28 days postnatal age. Demographic and clinical data, including laboratory parameters, the dose and the duration of lipid administration, and the amount of intravenous heparin, were analyzed. Results: Serum triglycerides were higher in the small for gestational age (SGA) infants than in the appropriate for gestational age infants ($185.5{pm}134.9$ mg/dL vs. $126.9{pm}101.9$ mg/dL, p=0.019). Birth weight, gestational age, and body weight were negatively correlated with serum triglyceride level (r=-0.289, p=0.002; r=-0.208, p=0.029; r=-0.287, p=0.002, respectively). The serum triglyceride level was statistically lower in preterm infants receiving 1 U/mL of heparin than in those receiving 0.5 U/mL heparin or no heparin. Conclusion: Preterm infants receiving parenteral nutrition, particularly SGA and extremely low birth weight infants, tend to have hypertriglyceridemia. Thus, administration of 1 U/mL of heparin rather than 0.5 U/mL or none may be helpful to prevent hypertriglyceridemia in preterm infants.