The clinical outcome of critical ill patients can be improved by standardised nutrition. However, trials meeting the standard of evidence-based medicine are rare. For this reason, standards still have to be based on pathophysiological considerations. We describe a concept of combined nutrition for critically ill patients which avoids hyperalimentation and considers also immunological aspects. An equivalent composition of enteral and parenteral nutrition allows a transition between both forms without problems. The nutritional goal is defined by multiplication of the base rate, i. e., body weight in kg as delivery rate in mL/h, - corresponding to 24 kcal/kg BW/24 h - with a target factor which varies between 0.2 and 1.8. Both forms of nutrition are complemented by immune-modulating substrates as glutamine and antioxidants.