Multisystem organ failure represents a major cause of mortality in intestinal ischemia and reperfusion (I/R), and oxidative stress plays a key role in its pathogenesis. Hypothermia is beneficial in I/R injury, but its effects on systemic oxidative stress have not been elucidated. The aim of this study was to evaluate the effects of moderate hypothermia on systemic oxidative stress after intestinal I/R injury. Anaesthetized adult rats (n = 10 per group) underwent 60 min of intestinal ischemia followed by 120 min of reperfusion or sham operation at normothermia (36 degrees C-38 degrees C) or moderate hypothermia (30 degrees C-32 degrees C). At sacrifice, ileum, liver, lungs, and kidneys were removed to determine the concentration of malondialdehyde (a marker of lipid peroxidation), reduced and oxidized glutathione (a major endogenous antioxidant), and glutathione redox state. Plasma malondialdehyde and nitrate plus nitrite (reflecting nitric oxide production) were also analyzed. A marked elevation of malondialdehyde was observed after I/R at normothermia in plasma, ileum, and lungs; however, hypothermia during I/R prevented this increase. I/R at normothermia caused a profound decrease in reduced glutathione and glutathione redox state in the ileum, but this was not observed in I/R at hypothermia. Interestingly, hypothermia increased glutathione content of control intestine. Nitric oxide production was increased only in normothermic I/R animals. Moderate hypothermia attenuates systemic oxidative stress associated with experimental intestinal I/R in an animal model by decreasing lipid peroxidation in plasma, ileum, lungs, and kidneys, by preventing the depletion of gut glutathione, and by reducing systemic nitric oxide production. However, whether these effects persist after rewarming is unknown.