Background: Lichen sclerosus is an inflammatory disease of unknown etiology affecting the anogenital skin and associated with the development of squamous cell carcinoma. It is not known whether long-term topical treatment with a potent steroid can cure this disease and thus prevent malignant evolution., Objectives: To analyze the rates of remission, recurrence, and chronic evolution of vulvar lichen sclerosus (VLS) treated with 0.05% clobetasol propionate ointment and determine whether this treatment can decrease the risk of malignant evolution., Design: Prospective study, conducted between 1981 and 2001, of 83 women with VLS who were treated until complete clinical and histologic remission and followed up for evidence of clinical and histologic recurrence (median follow-up, 4.7 years)., Setting: Dermatology department of a large urban teaching hospital., Results: Complete remission was obtained in 45 patients (54%). The probability of remission was significantly associated with age (P<.001). The estimated incidence of remission at 3 years was 72% in women younger than 50 years, 23% in women aged between 50 and 70 years, and 0% in women older than 70 years. The incidence of relapse was estimated to be 50% at 16 months (95% confidence interval, 30%-64%) and 84% at 4 years (95% confidence interval, 57%-94%). Age had no effect on relapse prevalence. The 8 observed vulvar squamous cell carcinomas (9.6%) occurred in previously untreated or irregularly treated VLS lesions., Conclusions: Treatment with a potent steroid cream can improve but does not cure VLS in women older than 70 years, probably because of a long disease evolution. In younger patients who achieve complete remission, it seems to have only a temporary effect. Although a protective effect from malignant evolution is suggested (carcinoma developed only in nontreated or irregularly treated VLS lesions), the number of seemingly protected patients was too small to be statistically significant.