This experimental study was designed to investigate the mechanism of Palmul-Tang(PMT) on the changes of cerebral hemodynamics in rats. The changes of cerebral hemodynamics in normal rats were as follows ; The PMT-induced increase in regional cerebral blood flow was significantly inhibited by pretreatment with indomethacin(1㎎/㎏, i.p.), an inhibitor of cyclooxygenase, and was inhibited by methylene blue(10㎍/㎏, i.p.), an inhibitor of guanylate cyclase. The PMT-induced dilation in pial arterial diameter was significantly inhibited by pretreatment with indomethacin and methylene blue. The PMT-induced increase in mean arterial blood pressure was significantly inhibited by pretreatment with indomethacin but was increased by methylene blue. This results were suggested that the mechanism of PMT was mediated by cyclooxygenase. The changes of cytokine production in cerebral ischemic rats were as follows ; In cytokine production of serum by drawing from femoral arterial blood after middle cerebral arterial occlusion 1hr, sample group was decreased IL-1β and TNF-α production compared with control group, IL-10 production of sample group was similar to that of control group, but sample group was significantly increased TGF-β production compared with control group. In cytokine production of serum by drawing from femoral arterial blood after reperfusion 1hr, sample group was significantly decreased IL-1β production compared with control group and decreased TNF-α production compared with control group. IL-10 production of sample group was similar to that of control group, but sample group was significantly increased TGF-β production compared with control group. In cytokine production of serum by drawing from femoral arterial blood after reperfusion 4 hrs, sample group was significantly decreased IL-1β production compared with control group, but IL-10 production of sample group was similar to that of control group. sample group was increased TNF-α and TGF-β production compared with control group. These results suggested that PMT had inhibitive effect on the brain damage by inhibiting IL-1β and TNF-α production, but by accelerating TGF-β production. The present author thought that PMT had an anti-ischemic effect through the improvement of cerebral hemodynamics and inhibitive effect on the brain damage.