Detection of papillomavirus DNA in situ hybridization technique was performed in 29 symptomatic patients (6 males and 23 females) during the period of 1989-1991 at the Clinic for Sexually Transmitted Diseases, Universidade Federal Fluminense, State of Rio de Janeiro. All the male patients had condyloma acuminata. Only HPV 6/11 were found in these lesions. Clinical features in the female patients included vulvar condyloma acuminata, bowenoid papulosis, flat cervical condyloma, cervical condyloma acuminatum and cervical intraepithelial neoplasia grade II (CIN II). We also found cases of condyloma acuminata associated to vulvar intraepithelial neoplasia grade III (VIN III), as well as to vaginal invasive carcinoma. HPV 6/11 and 16/18 were found in vulvar condyloma acuminata. Mixed infection by 6/11-16/18 HPV were also seen in these lesions as well as in the patient who had cervical condyloma acuminatum. HPV 16/18 were found in the condyloma acuminatum plus VIN III and in the CIN II lesions. We have found HPV 31/33/51 in the specimen of condyloma acuminatum plus invasive carcinoma. In order to investigate the ultrastructural aspects of HPV infection in genital tissue, the biopsies of three female patients were observed under electron microscope. Mature virus particles were found in the cells of a condyloma acuminatum as well as in the condyloma acuminatum plus invasive carcinoma case. In another sample, chromosome breakages were found in the nuclei of the infected cells although no viral particles were observed.