Abstract: Objective To approach the treatment efficiency of replication defective adenovirus carrying HSV/TK gene under control of the Human Telomerase Reverse Transcriptase(hTERT) promoter and gancyclovir (GCV) in nude mice xenografts model of prostate cancer. Methods We successfully build the model of human prostate cancer xenografts in BALB/C nude mouse. After injecting different concentration gradient of Ad-hTERT-HSV-tk in caudal vena, the same level of GCV was peritoneal injection. The anti-tumor efficacy was analyzed by index of tumor volume, tumor weight, relative tumor curative, and tumor growth curve. Results In the presence of GCV, Ad-hTERT-HSV-tk observably inhibited growth of human prostate cancer xenografts in nude mouse in a dose dependent and there was no inhibition plateau. GCV and Ad-hTERT-HSV-tk alone caused slight inhibition of tumor growth, which was not statistically significant as compared with the negative control group (P>0.05). Conclusion Ad-hTERT-HSV/tk/GCV system was highly effective and safe to inhiabit the growth of human prostate cancer xenografts. And it may provide a new idea for treating human prostate cancer.