〔Abstract〕 Objective To observe the effects of125I seeds brachytherapy on apoptosis of HCCC-9810 cholangiocarcinoma cells and Livin expression.Methods The study included 5 groups:blank control group, vacant shell group, and125I seeds group(0.5 mCiGy, 0.7 mCiGy and 0.9 mCiGy group). HCCC-9810 cholangiocarcinoma cells were cultured in vitro. RT-PCR was used to detect the expression of Livin mRNA in HCCC-9810 cholangiocarcinoma cells 48 h after treatment with125I seeds. The expression of Livin protein in the cells was indicated using Immunohistochemistry and Western Blot. Flow cytometry was performed to assess apoptosis by using annexin V-fluorescein isothiocyanate(Annexin V-FITC)/PI double staining. Results Compared with blank control group and vacant shell group, cell apoptosis rates of the three experimental groups were increased(P<0.05), also, the expression of Livin was significantly enhanced(P<0.05). Among the three experimental groups, the lowest expression of Livin along with the highest cell apoptosis rate were detected in 0.5 mCiGy125I seeds group; but the expression of Livin in 0.7 mCiGy125I seeds group was higher than that of another two groups, accompanying with the lowest cell apoptosis rate. However, there was no significant difference in Livin expression and apoptosis rate between blank control group and vacant shell group. Conclusion There is significant difference in ability to induce cell apoptosis among different doses of125I, which may be related to the ability to elevate Livin expression in HCCC-9810 cholangiocarcinoma cells. Radio-resistance may be related to the level of Livin(an apoptosis suppressor gene) gene expression in cholangiocarcinoma cells.