Male Fischer 344 rats were orally fed one of four diets (Osmolite HN, Alitraq, Impact, and Purina rodent chow). After 6 days, jejunal mucosal nitrogen content and thickness were normal in all groups. After 7 days, challenge withEscherichia coliintraperitoneally demonstrated no difference in survival for any dietary group. In a second study, acute protein-calorie malnutrition was induced by administering 5% dextrose orally for 10 days. Animals were refed for 7 days with one of the four diets. Serum albumin concentrations and intestinal mucosal nitrogen content and thickness returned to normal with each refeeding program. Challenge withE. coliafter 7 days of refeeding, however, again demonstrated no difference in survival for any dietary group. Specialized enteral feeding products, containing additional amounts of arginine, glutamine, glutamate, RNA, and omega-3 fatty acids, are no more effective than a standard enteral feeding product or rat chow in maintaining intestinal anatomy or restoring anatomy following fasting. Furthermore, we found no survival advantage for the specialized products followingE. coliperitonitis.