Oral mucositis is a common side effect of cancer therapies, particularly radiation therapy for head and neck cancer and various forms of chemotherapy. It commonly results in severe oral pain that can compromise the duration and success of cancer management. Hospitalizations are common because patients lose the ability to take anything by mouth due to severe pain and must have alimentation supported during this period. Pain management usually requires potent narcotic analgesia. Cancer therapy-related oral mucositis is commonly described as the most significant and debilitating acute complication associated with radiation therapy and chemotherapy. Until recently, cancer therapy-induced oral mucositis was thought to be a process involving the epithelium only. Evidence is building that the process of oral mucositis involves far more than just the epithelium, but includes multiple cellular processes of the submucosa as well. Many strategies have been evaluated to prevent oral mucositis, but the data is confusing since it is often conflicting. Therapy with the growth factor, KGF1, appears promising, as it is the only medication currently approved by the FDA. A multifaceted approach that targets the entire mucositis process will probably be needed to optimize overall prevention.