Abstract: Objective : To explore the effect of 5-Aza-2'-deoxycytidine on the growth of tumor and transcription regulation of DAPK gene in Xenografted of nude mice and to find new target of laryngeal cancer therapy. Methods The model of human laryngeal carcinoma xnograft in nude mice was set up. The growth of those xnografts in nude mice was observed and a growth curve of the xenografted drawn, after treated by 5-Aza-2′-deoxycytidine. RT-PCR and immunohistochemistry were used to determine the expression of DAPK mRNA and protein. Results : No significant difference for body weight of the nude mice was found between the medication group and the controls, after treatment with 5-Aza-2'-deoxycytidine. Volum of human nasopharyngeal carcinoma xnografts in the nude mice of medication group was smaller than those in controls. There was a statistically significant difference between the medication group and the controls, because no expression of DAPK was observed in the control group without treatment of 5-Aza-2ˊ-deoxycytidine. On the contrary, the expression of DAPK was observed in the treatment group. Conclusion : 5-Aza-2'- deoxycytidine may slow down the growth of tumor by reactivating tumor suppressor genes silenced by promoter methylation in vivo.