The purpose of the present study was to determine the effects of treatment with thyroxin and dexamethasone separately and together on I/R injury in newborn rat intestine. Newborn rats were divided into five groups: (1) control (C) group, (2) sham group, (3) thyroxin (T(4)) group, (4) dexamethasone (DEX) group and (5) thyroxin plus dexamethasone (T(4)+DEX) group. Each group consisted of seven pups. Group T(4) received thyroxin I mu g/g BW/day, group DEX received dexamethasone 5 mu g/gBW/day and group T(4)+DEX received 1 mu g/gBW/day thyroxin and 5 mu g/gBW/day dexamethasone i.p. for 7 days. Group C received only physiological saline (NaCl 0.9%). Animals were sacrificed at the end of the reperfusion period and ileum samples were obtained. Malondialdehyde (MDA) levels, a product of lipid peroxidation, glutathione (GSH) levels, a key antioxidant were determined in ileum homogenates. In the jejunum, only T(4) caused a significant statistical elevation in GSH compared with control, sham and DEX groups (p < 0.05). There was significant statistical interaction between T(4) and DEX treatment, i.e. the effect of T(4) treatment was greater in both regions. Mucosal damage scores showed statistical significant effect of T(4) in the ileum compared with control and T(4)+DEX group. The same significant statistical effect was seen with T(4)+DEX group compared to the control group in the ileum. Overall, the comparison between the two regions shows a powerful effect of T(4) in both regions. There was statistical significance between the scores of T(4) in the ileum and of DEX and T(4)+DEX in the jejunum. A beneficial effect of thyroxin in all samples was observed in this study supporting its protective effects against I/R injury which was attenuated by glucocorticoid administration.