Protective role of selenium against free radical damage was first demonstrated in the heart and this effect was further questioned in other systems. In the present study, the effects of exogenously administered selenium on intestinal fine morphology, lipid peroxidation, and bacterial translocation (BT) in experimental intestinal ischemia/reperfusion (I/R) model were examined. Thirty-two male Wistar rats weighing 250-300 g were randomized into four groups. Sham group (n = 8) underwent laparotomy only. In the I/R group (n = 8), laparotomy was performed and the superior mesenteric artery was occluded using an atraumatic microvascular clamp for 30 min. In corresponding selenium-treated groups (n = 8 each), sodium selenate was given 0.2 mg kg-1 day-1 intraperitoneally (i.p.) for 3 consecutive days, prior to surgery for either laparotomy only or with I/R. Twenty-four hours later, tissue samples from liver, spleen, and mesenteric lymph nodes were obtained under sterile conditions for microbiological analysis and further evaluation of I/R-induced intestinal injury. Ileum samples were fixed in 10% formaldehyde for histopathological evaluation. In the I/R group, the incidence of bacteria-isolated mesenteric lymph nodes, spleen, and liver was significantly higher than other groups (P < 0.05). Selenium supplementation prevented I/R-induced BT and significantly reduced the I/R-induced intestinal injury (P < 0.05). Tissue MDA levels from the ileum specimens of selenium-treated rats were significantly lower than that of the I/R group (P < 0.05). Our results provide evidence that the relationship between BT and lipid peroxidation in intestinal tissue is crucial. Selenium pretreatment reduces lipid peroxidation which contributes to the maintenance of intestinal mucosal integrity. © 2002 Published by Elsevier Science Ltd.