Dietetics and nutrition are new, expanding disciplines. Feeding man's cub to ensure the best physical, brain and psychic growth to reach the adult age in a "sane" state is the daily challenge of pediatric dieteticians. The role of dieteticians in a pediatric hospital is essential: optimizing sick children's nutrition. A child is highly vulnerable, above all when he is sick. Unappropriate feeding can put his growth and development, as well as his healing at stake. Numerous studies believe that denutrition in pediatric hospitals prevail by 7 to 45%. A survey has been carried out in two care units in the University Children's Hospital Queen Fabiola in Brussels. For one month, the nutritional hazard has been evaluated in every children admitted in these units. One observes that one third of these children shows a high nutritional hazard, and another third a moderate nutritional hazard. The tracking of the nutritional hazard and the appropriate nutritional care must be an integral part of the care given to any child admitted in hospital. A nutrition unit, with all the attending people involved (doctor, dietician, chemist, nurse), is necessary to improve the nutritional care of the patients.