Oriental medicine prescription has been used for the treatment of various clinical symptoms associated with cerebral apoplexy. However, single herb drug does not used cerebral apoplexy and there mechanisms of action have not been defined, and it is not yet known what effects they have on the hemodynamics of cerebral circulation. The study was aimed to investigate the effect batryticatus bombycis(BB) on the vascular systems including changes in blood pressure (BP), and regional cerebral blood flow (rCBF) and of male Sprague-Dawely rats. The changes in rCBF were determinated by laser-Doppler flowmetry. 1. Blood pressure was not affected by BB in rats. 2. rCBF was increased by BB in a dose-dependent manner. 3. Pretreatment with methylene blue(1mg/kg), and propranolol(1mg/kg) did not inhibited BB induced increased in rCBF. 4. Pretreatment with propranolol(1mg/kg) was increased by BB in a dose-dependent manner in blood perssure. 5. Pretreatment with ODQ($10{mu}g/kg$) and L-NNA(1mg/kg) were inhibited BB induced increased in rCBF. 6. Pretreatment with L-NNA(1mg/kg) was increased rCBF in a dose-dependent manner. These results suggest that BB causes a diverse response of blood pressure and regional cerebral blood flow(rCBF). The increased in rCBF is also mediated by nitric oxide synthease and guanylate cyclase.