Objective. The aim of this study was to demonstrate the neuroprotective effect of magnesium sulfate on ischemiareperfusion-induced injury in fetal rat brain. Methods.Twenty-four, 19-days pregnant rats were randomly allocated into four groups. Fetal brain ischemia was induced by clamping the utero-ovarian artery bilaterally for 20 min and reperfusion was achieved by removing the clamps for 30min. The control group consisted of noninjured rats. No treatment was given in the ischemiareperfusion group; whereas 1ml saline and 600mg/kg magnesium sulfate was administered in the vehicle and the treatment groups 30min before ischemia reperfusion injury. Lipid peroxidation in the brain tissue was determined as the concentration of thiobarbituric acid-reactive substances (TBARS) for each fetal rat. A one-way analysis of variance and post hoc test were used for statistical analysis. Results.TBARS levels were found to be increased after ischemia reperfusion injury when compared with controls. Magnesium sulfate treatment prevented the increase in TBARS after ischemia reperfusion injury. Conclusions.We have shown that magnesium sulfate decreases TBARS levels significantly in fetal rat brain subjected to ischemia reperfusion injury and may have potential therapeutic benefits by reducing oxidative stress after intrauterine ischemiareperfusion-induced fetal brain damage. © 2011 Informa UK, Ltd.