Abstract： The purpose of this study was to evaluate the influence of dosimetric difference in intensity-modulated radiotherapy (IMRT) on the short- and long-term efficacy, Oral Mucositis Assessment Scale (OMAS) and visual analogue scale (VAS) scores in patients with nasopharyngeal carcinoma (NPC) . The study prospectively included 120 NPC patients who received different doses of IMRT in our hospital. The short- and long-term efficacy, OMAS and VAS scores after IMRT were observed. Our study found that the 6-, 9- and 12-month local control rates in the high-dose group (92.50%, 95.00%, 97.50%) were significantly higher than those in the low-dose group (75.00%, 75.00%, 77.50%) . The 3-, 4- and 5-year survival rates in the high-dose group (75.00%, 60.00%, 50.00%) were also significantly higher than those in the low-dose group (45.00%, 30.00%, 22.50%) . In summary, proper increase in the dose of IMDT may result in improved therapeutic efficacy of NPC.