Lichen sclerosus (LS) is a chronic inflammatory disorder of the skin and mucosa, presenting to genitourinary physicians and dermatologists. It affects both sexes and all age groups. Although the exact aetiology is uncertain, genetic predisposition, infections and autoimmune factors have been implicated in its pathogenesis. Symptoms include pruritus and soreness, but asymptomatic presentations are not uncommon. The classical clinical picture is of atrophic white plaques in the anogenital region. Histopathology is specific with basal cell degeneration, upper dermal oedema, homogenization of collagen and a chronic inflammatory infiltrate. Short courses of potent topical corticosteroids form the mainstay of treatment. The condition tends to be remitting and relapsing, with spontaneous regressions reported in a few. In men, the term balanitis xerotica obliterans is sometimes used to describe late and severe LS of the penis. Scarring and progression to squamous cell carcinomas can occur in chronic LS, resulting in significant morbidity. A multidisciplinary approach to care and the need for long-term monitoring cannot be overemphasized.