Radiation-induced oral mucositis (OM) is common among patients with head and neck carcinoma (HNC), and is the single most debilitating side effect of radiation treatment. Acute, severe OM is associated with significant discomfort and impairment of the patient's ability to eat and swallow. OM also is related to breaks in treatment, the placement of feeding tubes, and hospitalization. Despite its frequency and clinical impact, risk factors for OM in HNC patients have not been well defined to date. The current study was undertaken to examine the risks and clinical consequences of OM in HNC patients who are receiving radiation therapy.