Lichen sclerosus is a chronic inflammatory skin disorder that has a predilection for the anogenital area. Topical corticosteroid is occasionally effective; however, continuous treatment is often required and recurrence after its stoppage is frequent. Herein, we report a case of vulvar lichen sclerosus in a 5-year-old girl, which was refractory to topical corticosteroids. After 14 weeks of treatment with 0.03% tacrolimus ointment once daily, the lesions completely resolved without side-effects. Of interest, the number of milia within the plaque of lichen sclerosus was reduced in tandem with the improvement of lichen sclerosus. This is the first report of topical low-concentration tacrolimus treatment showing a dramatic effect in the treatment of childhood vulvar lichen sclerosus.