OBJECTIVE To observe the clinical results and the toxicities of normal tissues in untreated nasopharyngeal carcinoma (NPC) treated with intensity modulated radiation therapy (IMRT). METHODS A total of 90 patients with untreated NPC received IMRT. According to the 1992 Fuzhou staging system, 3 patients were in stage I, 29 in stage II, 26 in stage III, and 32 in stage IVa. For IMRT,the prescription dose was 71.94-77.88 Gy/33f for the planning target volume of the gross tumor volume in the nasopharynx (PGTVnx); 69.96 Gy/33f for the positive neck lymph nodes (GTVnd); 60-66 Gy/33f for the planning target volume of the high risk regions (PTV1); and 50.4-56 Gy/28f for the planning target volume of the low risk regions (PTV2). Chemotherapy included concurrent and adjuvant protocols. The overall survival rate, local control rate, and distant metastasis-free survival rate were estimated by Kaplan-Meier method. Cox regression was used for multivariate analysis. Acute and 1ate toxicities were graded according to RTOG radiation morbidity scoring criteria. RESULTS The median follow-up time was 33 months (12-56 months). The 1-, 2-, 3- and 4-year survival rate was 97.8%, 90.6%, 86% and 80%; the local control tate was 98.8%, 97.5%, 92.1% and 77.4%; and the distant metastasis-free survival rate was 95.3%, 90.7%, 88.4% and 85.8%, respectively. The most serious acute toxicity was irradiated inflammation of mocosa with Grade 1 to 4 of 16.7%, 60%, 23.3% and 0, respectively. In the multivariate analysis, clinical stages were the prognostic factors for the survival rate. The most serious toxicity was salivary gland. The rate of grade xerostomia 1-year after the radiotherapy with Grade 1 to 4 was 18.1%, 9.6%, 0 and 0, respectively. CONCLUSIONS IMRT combined chemotherapy can improve the survival rate, and late adverse reaction is obviously decreased. Local recurrence and distant metastasis are the main reasons for low survival rate.