Outcomes research typically assesses three major health care outcomes, including quantity of life, quality of life (QOL), and health care cost. This article highlights the impact of treatment-associated mucositis on health care costs and QOL. After a background description of the economic analyses of overall cancer treatment costs and of the incremental costs associated with other treatment side effects, data from a retrospective study of mucositis-specific costs are presented. The second half of this article reviews current knowledge about the effect that mucositis has on QOL. Because the empirical work that specifically evaluates mucositis and QOL is quite limited, studies examining proxies for mucositis grading are described. These include studies comparing the QOL of patients currently undergoing treatment, in which symptoms likely to be associated with mucositis are worse, with that of patients who have completed treatment. Also discussed are investigations examining both the relationship between specific mucositis-associated symptoms, such as pain and difficulty swallowing, and QOL and the weighting of different domains of mucositis-associated problems. Finally, several future research directions are suggested, with the intent of expanding knowledge about the economic and QOL impact of mucositis in patients treated for head and neck cancer.