Renal fibrosis is a final common pathway of chronic kidney disease. SIRT1, a NAD+-dependent protein deacetylase, deacetylates the p65 of NF-κB and shows protective effects in kidney disorders. miR-373 directly targets the 3′UTR of SIRT1. However, roles of miR-373 in renal fibrosis are unclear. TGF- β 1, a critical regulator of fibrosis, was used to stimulate human kidney-2 cells to establish cell model for renal fibrosis. Unilateral ureteral obstruction (UUO) was performed as an in vivo model. TGF- β 1 induced the level of miR-373, reduced level of SIRT1, and promoted p65 acetylation and MMP-9 expression. These effects were reversed by the miR-373 inhibitor. In the animal model, UUO caused a consistent pattern as demonstrated in vitro. These results indicated an undesired effect of miR-373 in the regulation of renal injury and fibrosis by targeting SIRT1-mediated NF-κB/MMP-9 signaling, which might provide a potential therapeutic strategy for renal fibrosis. • MiR-373 suppressed the expression of SIRT1 and further promoted acetylation of NF-κB and the induction of MMP-9. • MiR-373 inhibition reversed the suppression of SIRT1, the promotion of Ac-NF-κB and the induction of MMP-9 induced by TGF- β 1. [ABSTRACT FROM AUTHOR]