Abstract: Objective To investigate the clinical effects and toxicity of intensity-modulated radiotherapy（IMRT） for untreated nasopharyngeal carcinoma（NPC） patients. Methods Seventy-four NPC patients receiving IMRT were enrolled from January 2005 to April 2011. The prescription dose was given 69.9 Gy／30f to the nasophaxynx gross tumor volume（GTVnx）， 69.9Gy／30f to positive neck lymph nodes（GTVnd）， 60Gy／30f to the first clinical target volume（CTV1） and 54Gy／30f to the second clinical target volume（CTV2）. The acute and late radiation injury were evaluated according to RTOG/EORTC criteria. KaplanMeier method was used to calculate the overall survival rate（OS）， distant metastasisfree survival rates（DMFS） and locoregional control rates from the last day of therapy. Results The median followup time was 39 months（range 13 to 80）. The 1-，2-，3- and 5-year survival rates were 97.3％，93.8％，88.2％ and 77.2％ respectively； 1-, 2-, 3- and 5-year DMFS were 93.2％，91.1％，91.1％ and 84.1％ and the 1-, 2-, 3- and 5- year loco-regional control rates were 98.6％，91.0％，86.8％ and 80.6％，respectively. The statistically significant difference in OS was found in different N stage（P＜0.05）， rather than for both clinical stage and T stage （P＞0.05）. Out of 12 failure patients， there were 6 with recurrence at the primary site（50.0％）， 2 patients in the neck（16.7％），and 7 patients（58.3％） by distant metastases. Among the 74 cases，3 cases had grade 3 xerostomia, one case had radio encephalopathy, four cases had grade 3 trismus. No patients suffered cranial nerves palsy. Conclusion The IMRT technique with the prescription dose of 69.9 Gy／30f to GTV provides favorable long-term effects with acceptable toxicity in NPC patients without distant metastasis. N stage is a prognostic factor for NPC patients.