Objective:To explore the suppressive effect of survivin antisense oligonucleotide on transplanted human breast cancer in nude mice. Methods:30 nude mice were transplanted with human breast cancer MCF7 cells to construct tumor models, which were divided into three groups (10 mice per group): Lipofectin, ASODN/Lip, and NODN/Lip were injected in to the tumor or around the tumor, respectively. A total of 3 injections were given, once every five days. Observations were made on tumor suppression rate, tumor volume and changes in weight of the animals. TUNEL method and transmission electron microscopy were used to investigate cell apoptosis of the tumor; western blot was used to detemine the expression of survivin protein in the 3 groups. Results:The subcutaneous tumor model in nude mice was successfully established. The tumor volume in the group of ASODN/Lip decreased during treatment, the rate of tumor suppression reached 70.10%; while the tumor volume of the other two groups increased. There was no statistical difference among the groups in weight changes of the 3 groups mice, the apoptosis rate in ASOND/Lip group was 38.6% detected by TUNEL and the rate was markedly higher than the other two groups(P<0.05). The expression of survivin protein in ASODN/Lip group decreased significantly. Conclusions:Survivin antisense oligonucleotide can effectively suppress human breast cancer cells growth rate in subcutaneous tumor of nude mice and accelerate the induction of apoptosis of tumor cells.