This study was conducted to determine the effect of an oral mucositis prevention protocol on nutritional status and quality of life for patients undergoing radiation therapy for head and neck cancers. This randomized, controlled, experimental study placed 20 patients in an intervention group where they received an oral care protocol and a nutrition protocol. Thirty patients were placed in the control group. Data were collected through face-to-face interviews using an oral assessment guide, oral evaluation guidelines, an oral toxicity scale, a visual analog scale, a subjective global assessment index, and a quality-of-life scale. As time post-treatment progressed, the prevalence of malnutrition in the intervention group was lower than in the controls group, and the intervention group experienced significantly less pain related to oral mucositis. Similar deteriorations in quality of life were noted in each group.