Abstract: Objective: To investigate the effects of soybean isoflavones(SI) on the expression of calcium-calmodulin dependent protein kinase(CaMK)Ⅱ in cerebral ischemia-reperfusion tissue in rats.Methods: Sixty adult healthy SD rats were randomly divided into the sham group,ischemia-reperfusion injury(I/R) group and SI pretreatment group(20 rats each group).The model of middle cerebral artery occlusion of rats were established by improving Longa's filament method.After 2 h of ischemia,the middle cerebral artery was reperfused for 24 h.The neurological behavior of the rats was scored using Longa's neurological function defect scale(NFDS),the cerebral infarction area was measured using TTC staining,and the expressions of CaMKⅡ was detected using Western blotting.Results: The score of NFDS in I/R group was obviously higher than that in sham group(P<0.01).Compared with I/R group,the NFDS score in SI group decreased significantly(P<0.01).The cerebral infarction volume in I/R group was higher than that in sham group(P<0.01).Compared with I/R group,the cerebral infarction volume in SI group decreased(P<0.01).The protein expression of CaMKⅡof the ischemic tissue in I/R group was lower than that in sham group(P<0.01).Compared with I/R group,the protein expression of CaMKⅡof the ischemic tissue increased in SI group(P<0.01).Conclusions: The mechanism of SI alleviating the cerebral ischemia/reperfusion injury maybe by upregulting the protein expression of CaMKⅡ in ischemic tissue.