Objective To investigate the late toxicities after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma and analyze the risk factors for treatment complications.Methods A total of 299 patients with nasopharyngeal carcinoma were given initial IMRT.The nasopharyngeal lesion and cervical lymph nodes were given a prescribed dose of 70 Gy ; the dose was 60 Gy to subclinical region ; the prophylactic dose was 54 Gy to the lower neck and supraclavicular region;these doses were given in 30 fractions over 6 weeks.The clinical records of 176 patients followed up were analyzed.The hazard factors were analyzed with Logistic method.Results The median follow-up was 52 months,and the follow-up rate was 99.7％.The most common radiotherapy-induced toxicities were xerostomia and hearing loss,with incidence rates of 54.5％ and 61.4％.The incidences rate of grade 0-1 adverse reaction of skin,subcutaneous tissue,or nasopharyngeal mucosa was 91.5 ％,93.2％,or 97.2％ ;the incidence rate of grade 1-2 trismus was 3.4％.Severe complications included cranial nerve injury (5 patients) and epistaxis (2 patients,one dying due to profuse epistaxis).The hazard factors for xerostomia and hearing loss were chemotherapy (x2 =7.38,P =0.007 ; x2 =7.96,P =0.005) and median doses to the parotid gland and inner ear (x2 =4.09,P =0.043 ; x2 =7.96,P =0.005).Conclusions Most patients develop only mild toxicity of the skin,subcutaneous tissue,or nasopharyngeal mucosa after IMRT.The incidence rates of xerostomia and hearing loss remain high owing to radiotherapy dosage and chemotherapy.