The pathogenesis of Fox-Fordyce disease has been reported to be hyperkeratosis and obstruction of the upper hair follicle, where the duct of the apocrine sweat gland opens. We report a case of Fox-Fordyce disease with full clinical manifestation. It appeared to be caused by the obstruction of intraepidermal apoeccrine sweat ducts by apoeccrine secretory cells detached and released from the secretory epithelium. A 24-year-old woman visited our clinic with intensely pruritic papules on axillae, mammary areolae, and pubic areas. Histopathologic examination revealed an obstruction of the sweat duct in the epidermis, which opened directly to the skin surface. The closing substance of the duct was an aggregate of epithelial cells, probably derived from the secretory portion. In the dermis, the secretory cells of apocrinelike sweat glands had been detaching from the secretory epithelia. These findings suggest that Fox-Fordyce disease can occur by the mechanism in which apoeccrine secretory cells obstruct sweat ducts. (J Am Acad Dermatol 2003;48:453-5.)