OBJECTIVE:To observe E-calcium sticky protein(E-cadherin) expression in kidney tissues in a rat model of unilateral ureter ligation and the effect of Yishen Huayu Fang(formula of tonifying the kidney and dissolving accumulated blood stasis) on the expression.METHODS:A total of 150 clean grade male rats were randomly divided into a control group,model group,low-dose Yishen Huayu Fang group(low-dose group),high-dose Yishen Huayu Fang group(high-dose group),and Lotensin group.A renal fibrosis model was established with unilateral ureteral obstruction(UUO).Pathological changes of rat renal tissue were observed with light microscopy on days 3,7,14,21,and 28 after UUO.Changes in kidney tissue E-cadherin expression were observed with immunohistochemistry.RESULTS:Three days after modeling,kidney edema appeared followed by gradual inflammatory cell infiltration,and part of the small tubules disappeared while the renal cortex thinned.Meanwhile,the E-cadherin expression level dropped,which was negatively correlated with the obstruction time.After intervention,E-cadherin expression was increased in all treatment groups(P