AIM: To investigate the effect of icariin on renal fibrosis and injury in hypertension through Cx32-Nox4 signaling pathway. METHODS: Models of hypertensive nephropathy (HN) were established in spontaneously hypertensive rats (SHRs). The experiment was divided into 4 groups: normal control group (WKY rats), model group (SHR), icariin 10 mg·kg-1·d-1 group (icariin once daily), icariin 30 mg·kg-1·d-1 group (icariin once daily), n=10. The expression of fibrosis-related proteins was detected in vivo. NRK-52E cells exposed to AngII were selected to observe the effects of icariin on kidney injury. Extracellular matrix (ECM) levels, including α-smooth muscle actin (α-SMA), collagen I (Col-I) and fibronectin (FN) expression were measured by Western blot and immunohistochemistry. The expressions of oxidative stress markers including superoxide dismutase (SOD) and malondialdehyde (MDA) were determined by the test kit. RESULTS: Icariin reduced renal fibrosis in SHR rats in vivo. Icariin down-regulated the expression of α-SMA, FN, and Col-I and protected hypertension-damaged kidney tissue from progressive fibrosis (P<0.05). Icariin increased the total SOD activity and decrease the MDA level in kidney and serum of SHR rats (P<0.05). In addition, icariin increased the expression of Cx32 and decreased the expression of Nox4 in the kidneys of SHR rats (P<0.05). Icariin had a protective effect on AngII-mediated NRK-52E cell damage and fibrosis. CONCLUSION: Icariin can improve renal tubulointerstitial fibrosis and delay the progression of HN. Renal protection may be attributed to the regulation of oxidative stress mediated by the Cx32-Nox4 signaling pathway.