To determine the role of human papillomavirus (HPV) in the etiology of sinonasal papillomas, 57 inverted papillomas including 5 cases associated with carcinomas, 16 exophytic papillomas, and 5 cases of columnar cell papillomas were examined for the presence of HPV DNA by in situ hybridization and polymerase chain reaction (PCR). The genetic studies were performed on the formalin-fixed, paraffin-embedded material. In only 6% of the 52 benign inverted papillomas was HPV DNA identified, whereas 69% of the exophytic papillomas were infected by HPV DNA. In none of the 5 cases with columnar cell papillomas could HPV be demonstrated. HPV 6/11 was identified in all of these HPV-positive cases. In the carcinoma area, HPV was detected in 2 (1 HPV 6/11 and 1 HPV 18) of the 5 inverted papillomas associated with carcinomas. The findings confirm the presence of HPV DNA in sinonasal papillomas. The results also indicate that HPV 6/11 may be involved in the pathogenesis of, solely, exophytic papillomas. We found that in situ hybridization and PCR seem equally sensitive in detecting HPV in sinonasal papillomas.