Extramammary Paget disease of the vulva was found in association with vulval adenocarcinoma in an elderly woman who also had a uterine prolapse. The characteristic histological appearances of extramammary Paget disease were masked by striking reactive changes in the squamous epithelium. Primary excision of both the intraepithelial and invasive disease appeared complete. However, a subsequent hysterectomy with repair of the prolapse revealed extramammary Paget disease in the upper vaginal mucosa and cervix, a finding which is very rarely described. Pathogenesis and diagnosis of extramammary Paget disease is discussed, with differential diagnosis and reference to immunohistochemical methods.