Allogeneic bone marrow transplant patients commonly have oral complications related to their disease or its treatment. Those reported include: xerostomia, mucositis, caries, infection, gingival hyperplasia, periodontitis, and graft-versus-host disease. These complications may be responsible for significant morbidity. This article reviews commonly reported oral complications of bone marrow transplantation and presents three cases in which intraoral pyogenic granuloma occurred. The cause of these lesions in post-bone marrow transplant patients is discussed.