Lichen planus is a unique but common inflammatory disorder that affects the skin, mucous membranes, nails and hair. Oral lichen planus (OLP) is among the more common mucosal conditions a clinician is likely to encounter in his or her practice. The etiology is unknown. Immunofluorescence studies have provided some insight into a proposed immunopathogenesis. Buccal mucosa, tongue and gingiva are more commonly involved. The question of malignant transformation of OLP remains controversial. Management of lichen planus can be challenging and discouraging for both the patient and physician. Treatment options should be assessed for attendant risks and benefits, and tailored to the extent and severity of disease.