The presence of human papillomavirus (HPV) 16 was studied by using the polymerase chain reaction (PCR) directly on sections histologically defined as normal squamous epithelium and metaplastic squamous tissue of the uterine cervix. Ten specimens of normal epithelium were obtained at hysterectomy from women with uterine leiomyoma. Six specimens of squamous metaplasia were adjacent to the areas of dysplastic epithelium in which HPV 16 DNA had been detected previously by PCR. HPV 16 DNA was amplified specifically and detected in two of 10 normal cervical epithelium specimens and in all of 6 squamous metaplasia specimens adjacent to dysplastic lesions. However, HPV DNA could not be detected in the metaplasia by in situ hybridization. These results suggest that metaplastic squamous tissue adjacent to dysplastic lesions harbors fewer copies of HPV DNA than the dysplastic area and the carcinoma and that the HPV copy number per cell may be relevant to the pathogenesis of cervical carcinoma.