OBJECTIVE: To investigate the association between clinical factors, oral dose-volume parameters during radiotherapy for nasopharyngeal carcinoma (NPC), and the development of severe radiation-induced oral mucositis (ROM). It also aims to identify predictive risk factors for severe ROM to support preventive strategies. METHODS: Clinical data from 175 NPC patients treated at Jiangxi Cancer Hospital between July 2023 and February 2024 were analyzed. The associations between clinical factors, oral dose-volume parameters, and severe ROM were assessed using univariate and multivariate logistic regression analyses. RESULTS: The incidence of severe ROM was 34.3% (60/175). Univariate analysis demonstrated significant correlations between severe ROM and dose-volume parameters, including V CONCLUSION: The irradiated oral mucosa volume at V