Lichen planus (LP) is a chronic disease of the skin and mucous membrane. Oral lichen planus (OLP), the mucosal counterpart of cutaneous lichen planus that presents with a variety of clinical features, about 25% present with oral lesions alone. Patients may develop white striations, white papules, white plaques, erythema, erosions, or blisters affecting predominantly the posterior buccal mucosa bilaterally. The clinical presentation of OLP ranges from mild painless white keratotic lesions to painful erosions and ulcerations. The diagnosis of OLP was based on history, clinical findings and histopathological features. There is no consensus on a single set of criteria for the diagnosis of OLP. Some investigators use only the clinical criteria, while others use both clinical and histopathologic criteria. Furthermore final diagnosis was confirmed by Immunohistochemical staining (IHC) with CD8 precursor cells. The possibility of this lesion to turn malignant justifies the importance of early definitive diagnosis and long term follow up for patients with such disease.