In recent years, improvements in care have significantly improved survival in preterm and, particularily, the very low birth weight infant (VLBW). While immediate survival can be directly related to pulmonary maturity, several studies stress the importance of timely and adequate nutrition in these high-risk infants on a short- and long-term [1]. Yet, nutritional support remains a very controversial issue in these high-risk infants. Early provision of adequate intakes may be limited by clinical instability and immaturity. At the same time, nutritional requirements and methods of nutritional assessment are not well defined. The aim of this paper is to outline some of the methods used during nutritional assessment in preterm infants with special reference to the measurement of body composition.