Objective To investigate influence of cisplatin (DDP) on the tumor inhibition rate, transcriptional levels of CyclinB₁ and CyclinD₁ of CNE-1 xenograft in nude mice. Methods Tumor mode of nude mice CNE-1 xenograft was established. Then mice were divided into control arm, DDP arm, high speed irradiation arm, simulated intensity modulated radiation therapy (IMRT) arm and simulated IMRT+DDP arm,with 12 mice in each arm. Irradiation dose was 20 Gy with a single fraction. DDP was 15 μg/g weight. The maximum diameter of tumor base was measured every other day. The growth curve was drawn and tumor inhibition rate werevcalculated after 40 days. The transcriptional level of CyclinB₁ and CyclinD₁ of xenograft was measured by RT-PCR. The results of different groups were compared with one-factor analysis of variance. Results Tumor inhibition rates of the control arm, DDP arm, high speed irradiation arm, simulated IMRT arm and simulated IMRT+DDP arm were －129.1%, －71.2%, 42.5%, 35.3% and 47.1%, respectively. There was significant difference between the high speed irradiation arm and simulated IMRT arm (P=0.034), but not between the high speed irradiation arm and simulated IMRT+DDP arm (P=0.222). The transcriptional levels of CyclinB₁ in the arms were 0.429, 0.386, 0.322, 0.354 and 0.268. There were significant differences between the high speed irradiationarm and the simulated IMRTarm or the simulated IMRT+DDParm (P=0.007 and 0.000). The transcriptional levels of CyclinD₁ in the arms were 0.716, 0.583, 0.348, 0.495 and 0.296, respectively. There was significant difference between the acute irradiation arm and the simulated IMRT arm (P=0.000), but there was no significant difference betweenthe high speed irradiation arm and the simulated IMRT+DDP arm (P=0.072). Conclusions Irradiation of 20 Gy single fraction, or combined with DDP are effective on the CNE-1 xenograft in nude mice, but DDP alone can only lower the tumor growth speed. Irradiation of 20 Gy single fraction,or combined with DDP, or DDP alone can reduce the transcriptional levels of CyclinB₁ and CyclinD₁. As the single therapeutic time is prolonged in IMRT mode, the tumor inhibition rate is reduce, and the reduce of the transcriptional levels of CyclinB₁ and CyclinD₁ is depressed, while combined DDP can compensate the decline of the biological effect.