Lichen sclerosus is a chronic disorder of skin and mucosa which affects patients of all age groups, particularly women, but also men. It is most commonly seen on the female genital skin, but it also occurs on extragenital areas. Most patients complain of itching and, less frequently, a burning sensation, dyspareunia, dysuria and painful defecation are reported. The cause of lichen sclerosus is largely unknown. However, it has been suggested that a genetic predisposition to inflammatory disorders, an immunological constitution, hormonal influences and local factors might play a role. Anogenital lichen sclerosus is associated with an increased incidence of malignancies, especially vulvular squamous-cell carcinomas. The life-time risk of developing this carcinoma is about 5%. Extragenital lichen sclerosus and lichen sclerosus in children do not seem to be correlated with malignancy. Potent local corticosteroids form the mainstay of treatment for lichen sclerosus. The condition is characterised by remissions and exacerbations. Long-term follow-up is required for the early diagnosis of malignant changes.