The expression of the E7 and L2 genes of HPV 16 was studied in benign and precancerous female genital lesions to evaluate their role in the development of dysplasias. Ninety biopsy specimens from 70 patients, selected on basis of dot blot DNA hybridization, were included in immunohistochemical and in situ hybridization analyses. In the HPV 16 DNA positive cases, L2 mRNA and E7 mRNA were detected in biopsies from 24 and 21 patients, respectively. L2 mRNA was found in eight of 16 cases of condyloma and mild dysplasia, and in 13 of 14 cases of moderate to severe dysplasia. The figures for E7 mRNA were 6/16 and 13/14, respectively. We found L2 mRNA in four of 12 normal or condylomatous specimens and E7 mRNA in only one of these. The detection rates for L2 and E7 mRNAs increased along with the severity of the lesions (P = 0.0064 and P = 0.0001, respectively). The L2 protein was found in one condyloma and in 12 dysplasias, eight of which were moderate or severe. The L2-antibody-reactive cells were localized in superficial layers of the epithelium. The detection rate for L2 mRNA and especially for E7 mRNA increased along with the histopathologic grade of the lesion.