Hematopoietic cell transplantation is used to treat malignancies, hematologic and immune deficiency states, marrow failure syndromes, and autoimmune diseases. Graft-versus-host disease (GVHD) is a clinical syndrome seen following allogeneic transplantation where donorderived immunocompetent T cells and inflammatory responses attack host tissues. GVHD can cause significant morbidity and even result in mortality. The oral cavity is a frequently involved site with clinical changes resembling autoimmune collagen vascular diseases. Recognition, diagnosis, and monitoring of oral GVHD can help with diagnosis and grading of GVHD and judging responses to therapy. Topical and local management of symptomatic oral GVHD can reduce oral symptoms that can interfere with oral function and quality of life, and can reduce the need for more intensive immunosuppressive systemic therapies.