15153 Background: In the present study, anti-neoplastic effect of rapamycin against cholangiocarcinoma was studied in vitro. Methods: Expression of mTOR in 4 cholangiocarcinoma cell lines, TFK1, HuCCT1, NOZW, and OZ was evaluated by real-time PCR. Then, the four cholangiocarcinoma cell lines were cultured with rapamycin (0, 25, 50, 100, 200 nM), gemcitabine (0, 0.5, 1, 2 μM), or both, and anti-proliferative effect was evaluated by MTT assay. Results: All the four cholangiocarcinoma cell lines expressed endogenous mTOR- mRNA. Level of expression was the highest in HuCCT1 (65.8), and the lowest in TFK1 (17.6). Then, rapamycin significantly inhibited the growth of all the four cholangiocarcinoma cell lines, in dose-dependent manner. Gemcitabine inhibited the growth of NOZW (48.4%) and HuCCT1 (48.9%), but less efficiently in TFK1 (5.9%) and OZ (27.4%). Furthermore, synergistic anti-proliferative effect of rapamycin and gemcitabine was observed in TFK1 (39.1%), NOZW (38.9%), and OZ (47.1%), not in HuCCT1 (18.9%). Conclusion: Rapamycin effectively inhibited the growth of the cholangiocarcinoma cell lines, and synergistic effect with gemcitabine was observed in three of the four cell lines. No significant financial relationships to disclose.