@@@@Objective To explore the effect of morroniside on blood viscosity in focal cerebral ischemia/reperfusion in rats. Methods The animal model was induced with occlusion of middle cerebral artery (MCAO), and morroniside (30 mg/kg, 90 mg/kg, 270 mg/kg) was then administered intragastrically for 7 d. Whole blood viscosity and plasma viscosity were detected with auto-hemorheological instrument and microplasma testing device. Results Compared with sham-operated group, both whole blood viscosity and plasma viscosity significant-ly increased in ischemic rats (P<0.001); however, morroniside reduced whole blood and plasma viscosity noticeably (P<0.001). Conclusion Morroniside can inhibit the increase of blood viscosity induced by focal cerebral ischemia/reperfusion in rats.