Subclinical vulvar lesions have been studied using the magnifying colposcope after 5% acetic acid application in 65 women with H.P.V. related cervical lesions and/or cervical intraepithelial neoplasms. Different vulvoscopic patterns are described: micropapillae (51%), diffuse acetowhite reaction (18%), papules (13%) and leukoplakia (11%). A normal appearance was found in 7% of the cases. Histological diagnosis is far different: normal histological appearance or minimal histological changes are noted in 57% of the biopsy specimens, flat condylomas of the vulva in 38% and vulvar intraepithelial neoplasms (V.I.N.) in 15%. The most frequent clinical aspects, i.e., acetowhite reaction and micropapillae are seldom related to V.I.N. The significance of these H.P.V. histologically-related vulvar lesions is still difficult to assess. Unlike cervical intraepithelial neoplasms, the malignant potential of V.I.N. remains uncertain. The risk of progression to invasive cancer in young women is low, probably less than 5%. On the other hand, vulvae may harbour H.P.V. able to influence subsequent recurrences of dysplasias of the cervix. Further studies are needed, especially Southern blot hybridization of vulvar biopsy specimens, to determine whether these histological abnormalities definitely harbour viruses and need subsequent treatment.