The benefits of specialty supplemented enteral diets administered to critically ill and critically injured patients and those undergoing major surgical procedures have been documented in a number of randomized prospective studies. It is unclear which nutrient or combination of nutrients causes the beneficial effects, but there are significant reductions in infectious complications depending upon the patient populations studied. It is imperative that the data be interpreted in the context of individual patient risk since specialty formulas appear most beneficial in patients at risk of subsequent complications or in those with significant pre-existing malnutrition. Although controversy exists regarding the use of specialty supplemented enteral diets in critically ill patients, they have been administered safely with minimal risk of adverse outcome in malnourished patients and in the critically ill and critically injured.