Objective: Moderately preterm (MP) (32-33 weeks) and late preterm (LP) (34-36 weeks) infants have higher risks of mortality and growth and developmental problems. We, herein present a new concept of nutritional assessment, total energy intake (TEI), which is the sum total of kilocalories administered in all nutrient forms.Methods: Fifty-two preterm infants were classified as MP (n=12), LP/appropriate for gestational age (LP/AGA) (n=33), or LP/small for gestational age (LP/SGA) (n=7). All groups received nutrient therapy by the same protocol. The sum of the daily energy intake at 14 and 28 days after birth was determined.Results: TEI was 2822.1162.1kcal/kg/28 days in the MP group, 3187.2 +/- 265.0kcal/kg/28 days in the LP/AGA group and 3424.6 +/- 210.4kcal/kg/28 days in the LP/SGA group. In all groups, TEI for 28 days was significantly correlated with body weight gain (r=0.465, p=0.006). TEI for 14 days after birth was inversely correlated with the body weight loss rate after birth (r=-0.491, p=0.0002).Conclusion: TEI was well correlated with anthropometric changes after birth. TEI may be used to effectively assess preterm infants' nutritional needs.