Objective:To study the potential effects of intensity modulated radiation therapy (IMRT) on clinical efficacy,oral mucosa reaction and immunological foundation;and to explore the effect of immunological changes on clinical efficacy and oral mucosa reaction in patients with nasopharyngeal carcinoma.Methods:A total of 200 patients with nasopharyngeal carcinoma,who came from First Department of Nasopharyngeal Radiotherapy,the First People's Hospital of Foshan from October 2008 to November 2011,were selected.The patients were treated with nasopharyngeal radiotherapy,and divided into an observation group and a control group (n=100 in each group).The control group underwent common conventional two-dimensional radiotherapy treatment,while the observation group underwent IMRT.The 5-year survival rates and recurrence rates were recorded at follow-up.After the radiotherapy,the oral mucosa in the patients were evaluated by the classification standard of acute radioactive mucositis by American Radiotherapy Oncology Group (RTOG),and the number of T lymphocyte subsets before and after treatment was detected.Results:There were significant difference in non-regional-recurrence survival rate,disease-free survival rate,local recurrence rate between the above 2 groups (all P＜0.05),but no significant difference in the distant metastasis-free survival rate (P＞0.05).The acute oral mucosa reactions of grade 1,2,3,4 in the control group were 8.00％,20.00％,12.00％,7.00％,respectively,and those were 7.00％,22.00％,15.00％,1.00％ respectively.There was no significant difference in the acute response of oral mucosa in grade 1,2 and 3 in the 2 groups (all P＞0.05),but there was significant difference in the grade 4 (P＜0.05).There were significantly difference in CD8+,CD4+/CD8+ and CD4+ T lymphocyte subsets before and after treatment in the above 2 groups (all P＜0.01);there were also significantly difference after treatment between the observation group and the control group (all P＜0.01).Conclusion:In the process of treatment in patients with nasopharyngeal carcinoma,the use of IMRT on the basis of chemotherapy is more effective than the conventional two-dimensional radiotherapy,which can reduce the proportion of grade 4 (severe) acute oral mucosa reaction.It may be related to the protective effect of IMRT on immune function in the patients.