〔Abstract〕 Objective To investigate the inhibitory effect of N-acetylcysteine(NAC) on the expression of inflammatory cytokines in human kidney proximal tubular epithelial cell induced by angiotensin Ⅱ(Ang Ⅱ). Methods HK2 cells were divided into four groups(control group, Ang Ⅱgroup, NAC group and Ang Ⅱ+NAC group). HK2 cells were treated with NAC(5 mmol/L), Ang Ⅱ(1 mmol/L) for 48 h. The levels of tumor necrosis factor α(TNF-α) and interleukin-6(IL-6) mRNA were detected by RT-PCR. The expression of TNF-α,monocyte chemotactic protein 1(MCP-1) and interleukin-1β(IL-1β) protein was detected by Western blot. The distributions of TNF-α were detected by immunofluorescence assay. Results Compared with the control group, the protein expression of inflammatory cytokines such as TNF-α, MCP-1 and IL-1β and mRNA expression(TNF-α, IL-6) increased in HK-2 cells when treated with Ang Ⅱ infusion. After NAC treatment, the above changes reduced in ang Ⅱ + NAC group, and the same results were showed by immunofluorescence technology. Conclusion N-acetylcysteine can inhibit the Ang Ⅱ-induced inflammation-related cytokines expression in human kidney proximal tubular epithelial cell.