BACKGROUND Many studies have proven that telomerase plays an important role during the occurrence and development of lung cancer, which has been an important target in gene therapy. The aim of this study is to explore the inhibitory effect of antisense oligodeoxynucleotides(ASODN) targeting human telomerase RNA on implanted tumor growth in nude mice. METHODS Implanted tumor models were Constructed in nude mice using human lung adenocarcinoma cell line A549. Eighteen Balb/C nude mice with implanted tumors were divided into three groups randomly: antisense oligodeoxynucleotide group(group ASODN), sense oligodeoxynucleotide group(group SODN), normal saline group (group NS), with 6 mice respectively. ASODs or SODNs mixed with Lipofectamine-2000 was injected into tumor directly every 24 h for fourteen days. RESULTS The inhibitory rates of tumor volume in Group ASODN and Group SODN were 43.94% and 6.91%, respectively. There was significant difference between the two groups(t =6.17, P<0.001). All the animals tolerated the drugs well and there was no nausea, vomiting and subcutaneous hemorrhage to occur during the therapy. The weight of the animals increased slightly at the end of experiment. CONCLUSIONS The results of this study suggest that intratumoral injection of human telomerase ribonucleic acid(hTR) ASOND could effectively inhibit the growth of implanted tumor in nude mice.