Herpes simplex virus (HSV) and human papillomavirus (HPV) sequences were analyzed in tumors of the female lower genital tract, by probing DNA from 13 intraepithelial and 30 invasive neoplastic lesions with radiolabelled HPV-16 and HPV-18 DNA as well as cloned fragments of HSV-2 DNA. Careful removal of stromal tissue from the pathological specimens allowed authentic tumor DNA to be processed. Normal genital tissue obtained from the patients and genital condylomata were included as internal controls. The presence of HPV-16 or 18 DNA was detected in 12/13 (92.3%) intraepithelial neoplasms and in 16/30 (53.3%) invasive carcinomas. No significant difference was detected in titer or frequency of antibodies to HPV group-specific antigen in sera from patients and controls. Hybridization to BgIII N fragment of HSV-2 DNA was detected in 4/13 (30.8%) intraepithelial neoplasms and 4/30 (13.3%) invasive carcinomas but in none of the control tissues. All the 8 samples harboring HSV-2 homologous sequences were also positive for HPV, supporting the hypothesis of a synergistic association between the 2 viruses. The hybridization analyses performed to study c-myc involvement in genital oncogenesis did not reveal c-myc amplification in either invasive or pre-invasive lesions.