Abstract: Objective : To investigate the effects of anti-sense peptide nucleic acids(AS-PNAs) targeting K-i67 mRNA on inhibiting expression of K-i67 and the growth of implanted human renal cell carcinoma in nude mice. Methods : 10nmol(0.1ml) AS-PNAs packed with liposomes were injected directly into implanted tumor in nude mice. The growth of tumor was observed. The gene Ki-67 expression of tumors was detected by immunohistochemical technique and Western blot method respectively, The apoptosis of tumors was detected by TUNEL assay. Results : The growth of tumor (513.2±64.2)mm3 was efficiently inhibited. The Ki-67 gene expression of tumors was significantly downregulated(23.0±2.4)%、(59.7±2.3) % by treatment of AS-PNAs. Apoptotic cells(31.1±2.0)% was increased by treatment of AS-PNAs. Comparing with AS-ODN treatment group. there were significantly difference between AS-PNAs group and AS-ODN group(868.9±128.2)mm3, (33.6±2.6) %, (85.7±4.4) %, (18.3±2.3)% (P<0.01). Conclusion : AS-PNAs targeting Ki-67 mRNA can inhibite the expression of Ki-67, induce the apoptosis of 786-0 cells and restrains the growth of tumor. The therapy effects of AS-PNAS is stronger than these of AS-ODN.