This study demonstrates the effects of Yanggyuksanhwa-Tang, Sasang constitutional herb prescription reported its clinical effect on the stroke of the So-yang In(少陽人), on the cerebral blood flow changes induced by nitro L-arginine methyl ester (L-NAME) treatment and ischemic brain damage induced by the middle cerebral artery occlusion (MCAO) in the rats. The changes of the arterial blood pressure, cerebral blood flow, and the diameter of the pial artery were measured in rats treated with L-NAME. And the changes of the infarct size, volume, and plasma tumor necrosis factor alpha ($TNF-{alpha}$) levels were measured in the rats that the middle cerebral artery has been occluded by the intraluminal suture thread method. Yanggyuksanhwa-Tang was administered by the i.v. injection on the L-NAME treated rats, by the i.o. administration on the MCAO rats. The results is 1. The changes of the arterial blood pressure was not different statistically between in the L-NAME treated control group and in the Yanggyuksanhwa-Tang administered group. 2. Increase in the cerebral blood flow induced by L-NAME treatment was attenuated in the Yanggyuksanhwa-Tang administered group significantly (P<0.05) as compared with the L-NAME treated control group. 3. Decrease in the diameter of the pial artery induced by L-NAME treatment was attenuated about 18% in the Yanggyuksanhwa-Tang administered group as compared with the L-NAME treated control group. 4. Ischemic damaged infarct areas were decreased significantly (P<0.05) in the interaural 12mm, 10mm, and 6mm brain sections of the Yanggyuksanhwa-Tang administered group as compared the MCA occluded control group. 5. Total ischemic infarct volume was decreased significantly (P<0.05) in the Yanggyuksanhwa-Tang administered group as compared the MCA occluded control group. 6. Plasma $TNF-{alpha}$ levels were decreased significantly (P<0.01) in the Yanggyuksanhwa-Tang administered group as compared the MCA occluded control group.