Post-transplantation lymphoproliferative disorder is a well-documented complication of solid organ or bone marrow transplantation. Histologically, it is characterized by an abnormal proliferation of lymphocytes, which can range from benign B-cell hyperplasia to malignant lymphoma. Non-Hodgkin's lymphoma (NHL) is associated with several risk factors, such as congenital or acquired immunodeficiency states, autoimmune disorders, and infectious agents (eg, Epstein-Barr virus). Primary sites of presentation in the head and neck are Waldeyer's ring, paranasal sinuses, salivary glands, the oral cavity, and the larynx. Clinical appearance of gingival NHL varies but is usually found to be an asymptomatic gingival enlargement or mass resembling a pyogenic granuloma. We present a patient with a gingival ulceration that was subsequently diagnosed as Epstein-Barr virus malignant lymphoma resulting from the immunosuppression needed to prevent graft-versus-host disease after bone marrow transplantation.