Lichen planus (LP) is an inflammation skin and mucous membrane disease that has characteristic clinical and pathologic features. Typical lesion of LP are small, flat-topped, polygonal, violaceous papules on the skin or reticular, white patch or plaque on mucous membrane. Nail involvement is manifested by longitudinal ridging, thinning and distal splitting and hair involvement is atrophic cicatrical alopesia. There was an increased risk of developing squamous cell carcinoma in the leasion of mucous membrane of oral cavity. Pathology of LP is the prototype of lichenoid interface dermatitis, which shows damage to the basal cell layer and a band-like dental lymphocytic infiltrate in close approximation to the epidermis. Other pathologic findings are compact orthokeratosis, wedge-shape hypergranulosis and irregular acanthosis. The treatment of LP in the main is largely symptomatic like antipruritic for itching. Therapies to suppress immune responses are commonly effective in treating LP, such as corticosteroid and cyclosporine topical or systemic. Other treatment are psoralene ultra violet A (PUVA) or steroids.