Tissue specimens from 15 patients with endobronchial papillary squamous tumours were probed for the presence of human papillomavirus DNA using the technique of in situ hybridization with probes to human papillomavirus genotypes 4, 5, 6b, 8, 11, 16 and 18. Despite the histological similarity of these lesions to known human papillomavirus-associated tumours no evidence of hybridization was detected in any of the cases analysed. It is thus unlikely that human papillomavirus has a significant role in the genesis of these tumours.