Optimalize the feeding of low birth weight infants is a very important problem in industrial as well as in developing countries where such infants are very numerous. Water need is very important but gastric and vascular capacity is limited in LBW infants. Energy has to be absorbed at a rate of 120 to 130 Kcal/kgBW/day without raising the osmolarity of the food. Protein intake has to be higher than in term babies but due to enzyme and kidney immaturity the amino acid pattern of the protein has to be carefully adapted to the pattern of the proteins to be synthesized. Calcium, phosphorus, iron, zinc and other trace minerals as well as vitamins have to be provided in relatively large quantities but their bioavailability has also to be checked. The utilisation of breast milk and particularly of own mothers milk having delivered prematurely is also discussed.