Group A beta-hemolytic streptococcus cause most vulvovaginal infections seen in prepubertal girls. Bacterial vaginosis is a common cause of abnormal vaginal discharge in women of childbearing age but is rare in children. Data are insufficient to suggest that bacterial vaginosis is an exclusively sexually transmitted disease. We report a 10-year-old girl with no history or suspicion of sexual abuse who developed bacterial vaginosis in the context of a lichen sclerosus being treated with tacrolimus ointment. Secondary bacterial infection in lichen sclerosus is uncommon. We speculate that the immunosuppressive effect of topical tacrolimus could have triggered the infection.