Objective : In this study, we used the aged bilateral common carotid artery occlusion (BCAO) rats were used to measure the effect of Bupleuri Radix (Si-Ho) on the brain ischemic injury, because aging is an important factor in storke, Method : The brian ischemic injury was induced by temporary closing of carotids on both sides in a low blood pressure state. Bupleuri Radix (Si-Ho) was orally administered in 18-month-old BCAO rats. Result : The Ischemic Damaged Hippocampus and HSP expression were analyzed by the immunohistochemical staining and the result were as follows: 1. The low numbers of pyramid cells in the hippocampus CA1 area for the ischemically injured experimental group rose to numbers simillar to those of the control group. 2. The thin neuronal cell layer in the hippocampus CA1 area for the ischemically injured experimental group returned to thickness simillar to those of the control group. 3. The normalized optical density of HSP70 expression was suppressed in CA2, DG and CA1 expression was significantly suppressed in the experimental group compared to the control group. Conclusion : These results suggested that Bupleuri Radix (Si-Ho) has a neuroprotective effect by reducing neural cell injury in the initial ischemic state.