OBJECTIVES: To determine a putative role and relation between human papilloma virus (HPV) and p53 in the etiology of sinonasal carcinomas associated with papillomas. STUDY DESIGN: The study group consists of all patients with sinonasal carcinomas associated with papillomas diagnosed in Denmark from 1980 to 1998. After reviewing our national pathological files, tumor tissues from 36 patients were collected, comprising 15% of the total cases of sinonasal carcinomas. In 35 cases a squamous cell carcinoma was demonstrated and in one case an adenocarcinoma was evident. Inverted papilloma was associated with carcinoma in 31 cases and exophytic papillomas in 5 cases. The material was investigated for HPV using polymerase chain reaction analyses with two sets of consensus primers (GP5+/GP6+ and MY09/MY11). The HPV-positive cases were submitted to dot-blot hybridization to establish the HPV type. Using immunohistochemistry, the p53 expression was determined. A p53 overexpression is defined as positive staining in 10% or more of the tumor cells. RESULTS: Among 30 examined cases of carcinomas associated with inverted papillomas, 4 cases were HPV-positive (13%). P53 overexpression was not shown among the HPV-positive cases, whereas p53 overexpression was seen in 21 of the 24 (88%) examined HPV-negative cases. Among the 5 carcinomas associated with exophytic papillomas, HPV was demonstrated together with p53 overexpression in 3 cases (60%). In addition, one case more was with p53 overexpression. CONCLUSION: An inverse relation between HPV and p53 overexpression in sinonasal carcinomas associated with inverted papillomas appears to have been demonstrated. HPV and p53 might also have an etiological role among the carcinomas associated with exophytic papillomas.