Optimal treatment strategies for cGVHD-related ulcerative stomatitis and related oropharyngeal pain have not been established. Therefore, there is a critical need to examine the pathogenesis of and to evaluate interventions for cGVHD-related ulcerative stomatitis and related acute oropharyngeal pain in the randomized controlled clinical trial setting to both advance the science of cancer treatment-related oral complications and to improve patient care. We hypothesize that the mechanisms of tissue injury occurring at the mucosal level leading to cGVHD-related stomatitis are similar to other types of stomatitis, such as cancer chemotherapy-related stomatitis and aphthous stomatitis, and are therefore amenable to treatment with anti-inflammatory strategies. Therefore, the purpose of this study is to elucidate the role of inflammation in GVHD-related ulcerative stomatitis by testing the efficacy of a topical thalidomide gel on the resolution of cGVHD-related stomatitis and related oropharyngeal pain. The actions of thalidomide, which include inhibition of the release of tumor necrosis factor-alpha (TNFa) and resultant alteration of the inflammatory cascade, may provide insight into the role of local mucosal inflammation in cGVHD-related stomatitis.