Artificial nutritional support does not alter the natural course in patients with malignant disease. The outcome of these patients is mainly determined by the type and stage of the underlying tumor. Progress of the underlying disease is often paralleled by malnutrition which in turn facilitates complications and may reduce survival and quality of life. Nutritional support can be applied to maintain body weight, immune function and quality of life. Enteral nutrition can be applied with a functioning gastrointestinal tract and has been proven to be superior compared to parenteral nutrition. Maintenance of intestinal mucosal function due to enteral substrate application prevents disruption of intestinal barrier function as well as the overgrowth of intestinal microorganisms. Using a step-by-step approach dietetic counselling in combination with augmented oral caloric intake should be the first measure. The next step to take is nutritional support by enteral tube feeding using formula diets. Parenteral feeding should only be used if other options to support caloric intake have failed.