In children with renal insufficiency, nutritional therapy is essential already in the early stage of the disease before dialysis treatment. The diet is supposed to supply energy and nutrients on the one hand, and the contribute to maintaining renal function on the other. Energy and protein supply are evaluated according to the recommendations of the Food and Nutrition Board (RDA 1989). This means a reduction of protein intake in nearly all children. In some patients, supplementation of energy is necessary.