Abstract: Objective: To evaluate the feasibility of using attenuated Salmonella as a tumor-targeting vector and to investigate the anti-tumor effects of co-expressed p53 and Survivin siRNA from a plasmid carried by attenuated Salmonella on prostate carcinoma in nude mice. Methods: A prostate cancer xenograft model was established in nude mice. Recombi-nant expression plasmids containing p53, siRNA-survivin, and siRNA-scramble and a co-expression plasmid containing p53 and siRNA-survivin were transformed into an attenuated Salmonella Ty21a strain. Attenuated Salmonella cells carry-ing the four types of plasmid were introduced by intragastric administration and intratumoral injection. In order to detect the Salmonella distribution and its gene delivery effects in nude mice, siRNA-survivin (containing green fluorescent pro-tein) carried by attenuated Salmonella was used as reporter gene. The products expressed by the vectors and their down-stream genes in the tumors were detected by RT-PCR, Western blot and immunohistochemistry. Results: Compared with the individual gene groups, the treatment combining p53 and siRNA-survivin showed an evident inhibitory effect on the tumor growth in nude mice with prostate cancer. In that group, the tumor size was smaller and the growth rate was lower.Flow cytometry showed that Salmonella could effectively transfer genes and the recombinant attenuated Salmonella strain could survive and express genes in the liver, spleen and tumor cells. Significant green fluorescence was observed in tumor tissues compared with the other organs. RT-PCR and Western blot demonstrated that p53 and GRIM-19 were overex-pressed and the Survivin gene was downregulated in prostate cancer cells after introduction of attenuated Salmonella carry-ing the p53/siRNA-survivin plasmid. Conclusion: Attenuated Salmonella carrying a plasmid that coexpresses p53 and Survivin siRNA shows a tumor-targeting effect and can inhibit the growth of prostate cancer in nude mice.