A total of 113 benign and malignant tumours of the mouth and upper respiratory tract have been analysed for the presence of papilloma virus DNA. Thirty-four (63%) of 54 papillomatous lesions were found to contain such DNA. Seventy-two percent of the laryngeal papillomas contained HPV 6 or HPV 11 DNA, whereas the oral papillomatoses harboured HPV 6 (15.6%), HPV 11 (9.4%), HPV 7 (9.4%), HPV 13 (12.5%) and HPV 32 (9.4%) DNAs. The high number of HPV 7 DNA-positive lesions was unexpected. In most of the malignant tumours no papilloma-viral DNA was found, with the exception of 3 tongue-base carcinomas, and in a metastasis from one of the tumours, which contained HPV 16 (3 biopsies) and HPV 2 related sequences (1 biopsy).