Oral mucositis is an inflammatory and ulcerative process of the oral cavity that results from an assault on the epithelial mucous membrane tissue and most commonly is associated with the administration of radiotherapy and chemotherapy. The incidence of oral mucositis ranges from 15%-40% in patients receiving stomatotoxic chemotherapy or radiotherapy and 70%-90% in bone marrow recipients. Knowledge regarding the pathophysiology of oral mucositis has evolved and now guides practice. Assessment tools to measure the level of mucositis provide valuable data concerning the status of the oral cavity. No single oral assessment tool has been found to be appropriate in all clinical settings. Mucositis has a significant impact on patients' quality of life and treatment plan. Management of oral mucositis is aimed at minimizing this side effect and its subsequent sequelae. The strategies of care are geared toward early intervention and supportive care for patients at risk for developing mucositis and include specific targeted therapies for the management of debilitating side effects. This article provides an overview of the risk factors, pathophysiology, incidence, impact, clinical presentation, oral assessment tools, management strategies, and nursing implications related to oral mucositis.