Abstract: Objective 　To study the effect of Herceptin on nasopharyngeal carcinoma (NPC) cells line growth in vivo and vitro. Methods 　Immounhistochemical assay was used to detect HER-2/ neu gene expression in NPC specimens ;the effect of Herceptin on NPC cells line growth were tested by ³ H-TdR incorporation in vivo and by model of xenograft s tumor nude mice in vit ro. Results 　HER-2/ neu gene overexpression was detected in NPC tissues ; the ³H-TdR incorporation of a NPC cells line CNE-2Z overexpressed HER-2/ neu gene was inhibited by Herceptin and Herceptin had the effect of tumor growth on xenograf t s tumor nude mice. Conclusion 　The ³H-TdR incorporation of NPC cells line CNE-2Z was inhibited in vit ro and the growth of CNE-2Z had been affected in vivo by Herceptin.