Glutamine is the major fuel for enterocytes and prevents mucosal atrophy in certain animal models. Previous studies in our laboratory have failed to show a trophic effect of glutamine on the small-bowel mucosa following massive resection when added to a chow diet. However, the complexity of the chow diet might potentially interfere with the adequate evaluation of the trophic effect of a single agent such as glutamine. This study was therefore designed to determine whether the addition of glutamine to an elemental diet would augment mucosal adaptation following massive small intestinal resection in a rat model. Male Sprague-Dawley rats were divided into two dietary groups, one receiving an amino acid-based pediatric elemental diet supplemented with 2% glutamine, and the other receiving the diet supplemented with 2% glucose. One half of the animals in each dietary group received 80% jejunoileal resection, and the remainder were sham operated. Fifteen days postsurgery, mucosal weight, DNA, protein, and sucrase activities were determined in both the proximal and the distal small intestine. While both groups of resected animals developed marked increases in all parameters of adaptation, the glutamine-supplemented group did not differ from the control diet group in any parameter. The addition of glutamine to an elemental diet had no enhancing effect on intestinal adaptation after bowel resection. These results are similar to those previously observed in our laboratory when glutamine was added to chow diet. The addition of glutamine to an elemental diet cannot be justified on the basis of its trophic effect in animals.