Immunonutrition may be superior to standard clinical nutrition in specific clinical situations. After severe trauma, an enteral immuno-enhancing diet, enriched with arginine, omega-3 fatty acids, and nucleotides, decreases infectious complications. During acute respiratory distress syndrome, a continuous enteral diet with high-dose omega-3 fatty acids, gamma-linolenic acid, and antioxidants improved clinical outcome. Glutamine should be administered enterally or parenterally whenever total parenteral nutrition is indicated.