Nutrition of intensive care patients is challenging due to complex metabolic changes. For this reason nutritional support adapted to the metabolic state is the only effective option to avoid hyperalimentation or hypoalimentation and thus has a direct influence on the prognosis. The analysis of the calorific requirement and the mode of administration are of key importance. An early enteral nutrition should be established, whereas in practice often a supplementary parenteral support is required to provide adequate calorie supply. Nowadays, most commercially available standard solutions are optimized concerning composition of nutrients; however, metabolic and gastrointestinal monitoring is recommended. In a selected group of patients the administration of immunomodulatory substances may be indicated but due to insufficient or conflicting study data an uncritical use of these supplements cannot be recommended.