Lichen sclerosus is commonly seen in middle-aged and elderly women but it affects both sexes, can occur at any age and anywhere on the body and has been reported in most races. Its aetiology is uncertain but there is an increased incidence of auto-immune antibodies in lichen sclerosus and an association with auto-immune disease such as vitiligo, thyroid disease and alopecia areata. Lichen sclerosus has been observed in different generations of a family but no consistent genetic pattern has emerged. Lichen sclerosus typically affects the anogenital region and presents with an intractable 'burning' pruritus. Extragenital lesions do not itch. Oral lesions occur in lichen sclerosus and may resemble lichen planus. Lichen sclerosus exhibits the isomorphic or Koebner phenomenon. The literature supports the view that lichen sclerosus is not a precancerous lesion but there is a significant association with vulval squamous cell carcinoma. Patients with inactive, treated lichen sclerosus should be reviewed annually. The treatment of choice of uncomplicated genital lichen sclerosus is a topical steroid of a potent or super-potent category. In males, circumcision may be indicated if topical measures are unsuccessful. In women, surgery is considered predominantly for cancer confirmed by tissue examination.