This brief review focuses on the effects of nutrient composition of enteral diets on the outcome of surgical patients and experimental models of infection. Complete enteral diets containing combinations of immunonutrients (arginine, glutamine, RNA, omega-3 fatty acids), when given postoperatively or after trauma to surgical patients, can reduce hospital stay, overall costs, and the incidence of wound complications and acquired infections. Immunonutrient diets can also reduce the length of hospital stay when given to patients admitted to the surgical intensive care unit. A high protein diet is usually required for optimal benefit, although administration of high protein immunoenhancing diets may have adverse effects in animals with severe untreated peritonitis because of a sustained overproduction of cytokines.