Objective To study the effects of moderate hypothermia on cerebral glucose and ATP contents and mitochondrial succinate dehydrogenase (SDH) activity in neonatal rats with hypoxic ischimic brain damage (HIBD). Methods Seven day old Sprague Dawley rat pups were subjected to ligation of the left carotid artery followed by exposure to hypoxia environment of 8% O 2 for 2 h, then they were randomly assigned into normothermic recovered group (IN group) and moderate hypothermic recovered group (IH group). The sham operated rats which were used as the control were assigned into the normothermic control group (NC group) and moderate hypothermic control group (HC group). The contents of glucose and ATP and activity of mitochondrial SDH were assayed at 0, 2, 6, 24, 48, 72 h after HIBD. Results The cerebal glucose contents in the IN and IH groups were significantly lower than those of the NC and HC groups 0 h after HIBD. Two hours after HIBD, the glucose content recovered to normal level. The concentration of ATP and activity of SDH in the IN group decreased first, then they recovered gradually and reached a peak 72 hours after HIBD. After 6 hours or 2 hours of HIBD, the ATP content or SDH activity of the brain in the IH group were significantly higher than those in the IN group. The ATP concentration was closely related to the SDH activity (r= 0.515 , P< 0.01 ). Conclusions Moderate hypothermia might protect brain tissue by inhibiting the decrease of SDH activity and increasing the synthesis of ATP