Mesenteric ischemia-reperfusion (I/R) injury to the intestine is a common and often devastating clinical occurrence for which there are few therapeutic options. -Melanocyte-stimulating hormone (-MSH) is a tridecapeptide released by the pituitary gland and immunocompetent cells that exerts anti-inflammatory actions and abrogates postischemic injury to the kidneys and brainstem of rodents. To test the hypothesis that -MSH would afford similar protection in the postischemic small intestine, we analyzed the effects of this peptide on intestinal transit, histology, myeloperoxidase activity, and nuclear factor-B (NF-B) activation after 45 min of superior mesenteric artery occlusion and 6 h of reperfusion. Rats subjected to I/R exhibited markedly depressed intestinal transit, histological evidence of severe injury to the ileum, increased myeloperoxidase activity in ileal cytoplasmic extracts, and biphasic activation of NF-B in ileal nuclear extracts. In contrast, rats treated with -MSH before I/R exhibited intestinal transit and histological injury scores comparable to those of sham-operated controls. In addition, the -MSH-treated rats demonstrated less I/R-induced activation of intestinal NF-B and myeloperoxidase activity after prolonged (6 h) reperfusion. We conclude that -MSH significantly limits postischemic injury to the rat small intestine.