Using a PCR strategy which detects disruptions in the E2 reading frame we have analysed the progression of human papillomavirus type 16 (HPV-16)-positive cervical lesions. From a total of 192 samples analysed, we detected HPV-16 in 74. In samples from the spectrum of inflammatory states and cervical intraepithelial neoplasia (CIN) grade I lesions we detected episomal forms of the virus. In invasive tumours and in samples from CIN III lesions there were no episomes detected, suggesting that lesions with integrated HPV-16 precede the invasive stage. The RT-PCR analysis demonstrated the presence of E6 transcripts at all stages and E2 transcripts in all early lesions. The E2 transcripts were not detected in 26 out of 29 CIN III lesions and tumours in which there was a disruption in the E2 gene. In tumours with E2 gene disruptions, we used single-primer PCR to demonstrate the presence of E2 gene sequences.