Abstract: Objective To explore the effect of telmisartan on the expression of metadherin in the kidney of mice with unilateral ureter obstruction. Methods Eighteen male C57 mice were randomized into sham-operated group, model group and telmisartan treatment group. In the latter two groups, renal interstitial fibrosis as the result of unilateral ureter obstruction (UUO) was induced by unilateral ureteral ligation with or without telmisartan intervention. Renal pathological changes of the mice were assessed using Masson staining, and immunohistochemistry and Western blotting were used to detect the expression of extracellular matrix proteins and metadherin in the kidney of the mice. In the in vitro experiment, cultured mouse renal tubular epithelial cells (mTECs) were stimulated with transforming growth factor-β1 (TGF-β1) and transfected with a siRNA targeting metadherin, and the changes in the expressions of extracellular matrix proteins and metadherin were detected using Western blotting. Results The expressions of extracellular matrix proteins and metadherin increased significantly in the kidney of mice with UUO (P<0.05). Intervention with telmisartan significantly lowered the expressions of extracellular matrix proteins and metadherin and alleviated the pathology of renal fibrosis in mice with UUO (P<0.05). In cultured mTECs, siRNA-mediated knockdown of metadherin obviously reversed TGF-β1-induced increase in the expressions of extracellular matrix proteins and metadherin. Conclusion Telmisartan can suppress the production of extracellular matrix proteins and the expression of metadhein to attenuate UUO-induced renal fibrosis in mice.