Glutamine (GLN) is an important fuel and epidermal growth factor (EGF) is a potent mitogen for intestinal mucosa cells. GLN-enriched parenteral nutrition was administered to male Wistar rats, and subcutaneous injections of EGF were given for 3, 6, and 7 days. Control animals were fed a non-GLN-containing solution. Other groups of animals received GLN or EGF alone. Mucosal samples were obtained from the jejunum, ileum, and colon for measurement of weight, DNA, protein, and mucosal thickness. Disaccharidase activity was measured in the jejunum. After 3 days, only animals that received both GLN and EGF had a significant increase in small-bowel mucosal protein and thickness relative to controls. A similar pattern was observed in the colon, where animals that received both agents had a greater mucosal thickness, DNA, and protein content than controls. At 7 days, animals that received EGF or GLN had greater nitrogen retention. In addition, animals that were treated with EGF had elevated sucrase and maltase activity compared with GLN-fed animals at this time. Animals treated with GLN and EGF tended to have increased sucrase activity relative to controls. GLN feeding was associated with increased mucosal DNA and protein contents throughout the intestine for the combined series. EGF increased mucosal DNA and protein in the small intestine but not in the colon. The effect of EGF on the protein content of the small-bowel mucosa was dose dependent. The effects of GLN and EGF on the small bowel and colonic mucosa were additive. These studies suggest that specific nutrients and hormones may be used in combination to decrease the mucosal atrophy that commonly occurs after gut disuse or disease.