The oral lichenoid lesion(OLL)is response that occurs on the oral mucosa.The OLL include allergic response to the dental materials,drugs,and on graft-vs-host disease(GVHD).OLL to dental material happen when restorative materials,most commonly amalgam,are in direct contact with the mucosa in sensitized individuals.Medications that produce OLL are oral hypoglycemic agents,angiotensin-converting enzyme inhibitors,and nonsteroidal anti-inflammatory agents.GVHD is a complication in bone marrow transplantation and OLL is a common lesion observed in this disease especially in chronic GVHD.The clinical and histological aspects of OLL are similar to oral lichen planus and turn it difficult to make a differential diagnosis.The purpose of this paper is review about OLL related to the dental materials,drug use and GVHD.