Recent investigations have suggested human papillomavirus (HPV) to be involved in the development of sinonasal papillomas (SNP). Forty-three patients operated for SNP were studied to determine the prevalence of HPV-DNA sequences in these tumours and to evalulate their value as a prognostic parameter. The original sections of all cases were reviewed and reclassified according to the WHO. Paraffin blocks available from 37 patients were subjected to in situ hybridization (ISH) and polymerase chain reaction (PCR). Histology revealed 34 cases of inverted papilloma (IP) (79 per cent), five cases of exophytic papilloma (EP) (12 per cent) and four cases of columnar cell papilloma (CCP) (nine per cent). Recurrences developed in seven of 41 patients (17 per cent), and malignancy occurred in four of 43 patients (nine per cent). HPV was detected in four of 37 specimens (11 per cent) both by ISH and PCR. In particular, HPV-11 was found in three lesions (two EP, one IP) (eight per cent), and HPV-6b was detected in one lesion (one EP) (three per cent). Our findings suggest a possible role for HPV in the pathogenesis of exophytic papillomas. As no correlation was found to malignancy and recurrence of disease, screening for HPV seems not to be useful as a prognostic parameter.