Objective:To study the effect of mitochondrial dysfunction on hippocampal cell apoptosis in kainite acid-induced epilepsy in rat. Methods:Kainite acid-induced epilepsy model was induced by injection of kainite acid into the hippocampus. Forty SD rats were randomly divided into five groups: the control and KA group(6 h,1 d,3 d,7 d),n = 8 for each group. The concentration of free calcium ion,ATP,and ADP,mitochondrial membrane potential,the activities of the mitochondrial respiratory chains complexⅡand Ⅳ,Na+-K+-ATPase in hippocampus were detected. Results:In the hippocampus,the concentration of free calcium ion was increased significantly,and mitochondrial membrane potential,the activities of the mitochondrial respiratory chains complexⅡand Ⅳ,Na+-K+-ATPase,and the concentration of ATP were significantly decreased in a time-dependent manner. Conclusion:Mitochondrial dysfunction may cause hippocampal cell apoptosis in kainite acid-induced epilepsy in rat.