The polymerase chain reaction (PCR) was used to investigate the prevalence and distribution of human papillomavirus (HPV)-16 DNA in paraffin sections of all pelvic lymph nodes removed from 14 patients with Stage Ib-cervical cancer at the time of resection of their primary tumours. The results were compared with those obtained from 8 women with no known history of cervical abnormality. In all, 22 cervical biopsies and 40 I lymph nodes (296 paraffin blocks) were examined. Nine of the 14 cervical cancer patients had primary tumours that were positive for HPV-16 DNA: only 3 of these had lymph nodes with histological evidence of metastasis, and HPV 16 DNA was detected in each of the corresponding paraffin blocks. HPV 16 DNA was also detected in varying proportions (8%-92%) of the histologically-negative lymph nodes from these women. There was no correlation between the HPV DNA-positive lymph nodes and their proximity to the primary tumour. HPV-16 DNA was not identified in any of the lymph nodes from the 5 women whose cancers were not HPV-16-related, or in those of women with no evidence of cervical abnormality. This preliminary survey suggests that HPV DNA is frequently transported from HPV-16-related cervical tumours to regional lymph nodes. However, its practical significance will not be clear until sufficient time has elapsed for correlation of the results with the clinical outcome.