We report a case of Jacquet erosive diaper dermatitis (dermatitis syphiloides posterosiva) in a 9-year-old girl suffering from urinary incontinence due to an ectopic opening of a left double ureter into the vaginal vestibule. The toilet paper that she used as an absorbent was thought to be one of the factors causing the eruption. The lesions cleared with topical application of a nonsteroidal antiinflammatory ointment and zinc oxide ointment, in conjunction with the use of sanitary napkins.