Aim To observe the effects of Ligan compounds in Fructus Forsythiae on ischemia/reperfusion(IR) rats models and the expression of endothelin3(ET-3) and glial fibrillary acidic protein(GFAP) in the models' hippocampus CA1 area,and to study the neurons'protection of Ligan compounds in Fructus Forsythiae and its value of treatment on ischemia/reperfusion imparement. Methods Forty-eight adult male mice were randomly divided into three groups: ①Ischemia/reperfusion group(n=24),the mice were subdivided into 1 day,3 days,5 days and 10 days(1 d,3 d,5 d and 10 d) subgroups according to reperfusion time after 7 minutes bilateral common cariod artery(BCCA) occlusion;② Ligan compounds in Fructus Forsythiae treatment group,the mice were given Ligan compounds in Fructus Forsythiae pre-operation and postoperation(n=18);③Sham-operated group(n=6) which was control group,only was exposed their BCCA,but not given 7 minutes BCCA occlusion.The expression of ET-3 immunoactivity were detected in the rats' hippocampus CA1 area by immuno-histochemisty. Results The number of ET-3 and GFAP immune positive cells in ischemia/reperfusion models'hippocampus CA1 area was increased compared with sham-group(p<0.01),the peak-time was the fifth day.While the number of ET-3 and GFAP immune positive cells in Ligan compounds in Fructus Forsythiae treatment group models'hippocampus CA1 area was decreased obviously compared with ischemia/reperfusion group. Conclusion The expressions of ET-3 and GFAP were up-regulated after IR,ET-3 is perhaps a destroying factor during reperfusion,astrocytic activation participated in the pathological process,while Ligan compounds can inhibit the process by getting rid of free radicals and exert the brain protection.