Objective: To investigate the effective of Sanhua decotion(三化汤) on early brain water content,penetration of blood brain-barrier and the expression of aquaporin4(AQP4) in rats with acute cerebral ischemia/reperfusion(I/R).Methods: The string inserting method was employed to reproduce the rat model of focal cerebral I/R SD rats were randomly divided into sham operation group,model group and Sanhua decotion group.After I/R,each group was then divided into 6 hours,12 hours,24 hours,48 hours and 72 hours five subgroups.The brain water content was detected by the ratio of wet/dry weight to evaluate cerebral edema and the blood-brain barrier(BBB) damage was observed by Evan′s blue(EB) staining.The AQP4 mRNA and protein expressions were measured by reverse transcription-polymerase chain reaction(RTPCR) and immunohistochemistry respectively.Results: Compared with sham operation group,the brain water content,EB content,AQP4 protein and AQP4 mRNA expressions were increased at every time point after I/R in the model group(P