Glutamine is an essential nutrient for the intestinal mucosa and other rapidly dividing cells. Glutamine is not present in standard parenteral nutrient solutions. When glutamine is added to both parenteral and enteral formulas, there is enhanced mucosal cellularity and repair. These changes are related to diminished mortality and morbidity in selected animal models. Glutamine-containing solutions are now being administered safely to patients. Studies are required to determine the effects of such therapy in individuals following extensive radiation or chemotherapy, major burns or infections and those with inflammatory bowel disease. It appears that selected nutritional support utilizing glutamine-containing nutrition can now be provided to maintain and support growth of the gastrointestinal mucosa.