The respiration of human brain mitochondria was measured by the Warburg's manometer and the members of the TCA cycle were used as the substrate. The O(2)-uptake of the non-epileptic brain mitochondria is about on and half times of the epileptic brain mitochondria. On the oxidation of the substrate: Malate, fumarate, pyruvate, oxalacetate and α-ketoglutarate accelerate the O(2)-uptake in both cases, and the O(2)-uptake of non-epileptic cases are always 2 or 3 times of the epileptic cases. Citrate accelerate the O(2)-uptake in the non-epileptic case, but not in the epileptic case. Succinate accelerate the O(2)-uptake in both cases and its about several times of the other substrate. Especially the increase of the O(2)-uptake of the epileptic brain mitochondria by succinate is higher than of the non-epileptic brain mitochondria.