We previously showed that intravenous total parenteral nutrition supplemented with nucleosides and nucleotides (NS/NT) promoted ulcer healing in rats with indomethacin-induced ileitis. The present study evaluated whether dietary NT supplementation would similarly affect ulcer healing in this model. Female Lewis rats were randomized into either control or experimental groups receiving yeast RNA containing NT or arginine, glutamine, fish oil, guar gum, or a combination of yeast RNA+arginine diets. Ileitis was induced by two doses of indomethacin (7.5 mg/kg) administered subcutaneously 24 hr apart. Ulcer number and length were determined at 4, 8, and 14 days after induction of ileitis. Ileal villous and crypt length, crypt-villous ratio, and bromodeoxyuridine (BrdU) labeling were studied in the control and yeast RNA-supplemented diet groups. Ileal ulceration was present in all groups at 4 and 8 days and was almost healed by 14 days. Rats receiving yeast RNA, arginine, and yeast RNA + arginine diets showed a significant decrease in ulcer number (56%, 28%, and 34%, respectively) and length (67%, 41%, and 48%, respectively) compared to controls at 8 but not at 4 days. Glutamine, fish oil, and guar gum had no effect on ulcer healing at 4, 8, or 14 days. Among the histological parameters, a significant decrease in crypt length in the yeast RNA-supplemented group at 8 days suggested an acceleration of the healing process and restoration to a near-normal crypt-villous architecture. We conclude that the yeast RNA, arginine, and yeast RNA + arginine diets accelerated ulcer healing, as indicated by decreased ulcer number and length. We postulate that the underlying mechanism(s) contributing to ulcer healing may be related, in part, to increased cell proliferation.