【Abstract】Objective To study the antitumor activity of HSVtk/CD combinative gene toward human cholangiocarcinoma in vivo. Methods Nude mouse models with transplanted subcutaneous cholangiocarcinoma were constructed and divided into 4 groups randomly, each group had 8 mice. Adenovirus solution free from suicide gene was injected in subcutaneous tumors of each mouse of control group. Adenovirus solution containing cytosine deaminase (CD), thymidine kinase (tk) and HSVtk/CD fusional gene were injected into single suicide gene either HSVtk or CD was transinfected into the tumor cells by injecting viras into subcutaneous tumor of mice of CD gene,tk gene and fused CD and tk gene group respectively. 24 hours after the injection, 5fluorocytosine (5FC) and ganciclovir (GCV) were injected introabdominally in each mouse. Growth of the tumors were monitored.Results Tumor growth of the genetransfection groups was suppressed in different degrees. Compared with the control group, the suppressing rates of the genetransfection groups were 41.2%, 55.7% and 70.0% respectively (P<0.05). Histological examination showed good tumor growth in the control group, and tumor necrosis in the other 3 groups, particularly obvious in the group transfected with pAd(HSVtk/CD).Conclusion Combinative gene system has a b antitumor effect on cholangiocarcinoma in vivo. But it’s not powerful enough to eliminate tumor thoroughly because of insufficient “Bystander effect”.