This experiment was done to investigate the antioxidant effect of Ondamtang(ODT) on brain tissues of rats. The experimental groups were divided into three groups and treated as follows for a fifteen days ; Negative control group(NC), Vitamin E admistrated group(PC), ODT administrated Group(ODT). After the extracting microsome from brain of rats, those were measured the amounts of Malondiadehyde and Hydrogen peroxide, then activities of antioxidant enzymes like Superoxide dismutase, Catalase and NADPH-cytochrome P-450 reductadse. The results were as follows; 1. In TBA reaction to measure the amount of MDA, oxidant material of brain tissue of rats, the group treated by ODT showed significant decrease. 2. In the formation of Hydrogen peroxide, the group treated by ODT showed no change in comparison with normal group. 3. The activity of SOD in the group treated by ODT showed a little increase in comparison with normal group. 4. The activity of Catalase was increased significantly in the group treated by ODT than normal group. 5. The activity of NADPH-cytochrome P-450 reductase in the group treated by ODT showed a little increase in comparison with normal group. According to the above results, it is suggested that Ondamtang(ODT) has some antioxidant effects on tissues of brain.