Objective To investigate the possible role of valsartan(Val) in transdifferentiation of human renal tubular epithelial cell line(HKC ). Methods HKC cells were divided into four groups: (1) serum-free (negative control); (2) MCP-1 + AAI-treated (positive control); (3) Val-treated alone; (4) Val-inhibition(treated with MCP-1 + AAI + Val). Then the expression of vimentin, α-smooth muscle actin (α-SMA ) of HKC cells were assessed by indirect enzyme immunohistochemistry (IEI), and the percentage of α-SMA(+ ) HKC cells was assessed by flow cytometry. Results No difference in expressions of vimentin and α-SMA by IEI and the percentage of α-SMA(+ ) HKC cells by cytometry were found between serum-free control HKC cells and Val treated ones. The expressions of vimentin and α-SMA in positive controls were markedly stronger than negative controls; while these expressions in Val + MCP-1 + AAI-treated HKC cells were less strong than those in positive controls. The percentage of α-SMA(+ ) HKC cells in the positive controls was significantly higher than that in negative controls(91. 8% vs 3. 1%, P < 0. 05), while the percentages of α-SMA(+ ) HKC cells in MCP-1 + AAI + Val group at Val doses of 0. 1, 1. 0, 10. 0 pg/ml (17. 3%, 32. 4%, 10. 0% )were dramatically lower than that in positive controls(P < 0. 005 ). Conclusions (1 ) No influence of valsartan on transdifferentiation of normal HKC cells in vitro was found in this study. (2) Valsartan may inhibit the transdifferentiation of HKC cells induced by synergistic effect of MCP-1 and AAI in vitro.