This article reports a study designed to evaluate the effectiveness of regular oral care protocol developed specifically for adults in intensive care to prevent mucositis. Data were collected using oral mucositis assessment scale, oral cavity assessment tool, and the National Cancer Institute Common Toxicity Criteria. The results indicated that oral mucositis can be reduced through the practice of administering oral care in accordance with oral health care guidelines. Oral care implemented in line with an evidence-based oral care guide and frequent observation of patients is the most important step in preventing oral mucositis.