Background: Inverted papilloma(IP) of the nasal cavity and paranasal sinuses is a benign neoplastic condition that can be associated with squamous cell carcinoma (SCC). Several studies have indicated an etiologic role for viruses in the development of inverted papilloma. And it is necessary to find out the significance of a biologic markers such as p53, c-erbB-2 to predict the malignant potential. The purposes of this study are to detect HPV in inverted papilloma of the nasal cavity and paranasal sinus, to examine role of HPV as an etiological agent, to examine the relationship between HPV subtype and malignant transformation of inverted papilloma, and to investigate the relation between expression rate of p53, c-erbB-2 and HPV in recurrent or malignant transformation cases. Material and Methods: Thirty two cases of inverted papilloma(IP) in the nasal cavity and paranasal sinuses were reviewed and classified into 3 groups; simple IP, IP with dysplasia group, IP with squamous cell carcinoma group. Paraffin embedded achival tissue was used in this study. The HPV was detected by in situ hybridzation (ISH) using HPV type 6/11, 16/18, 31/33/35 DNA probes. Expression of p53 and c-erbB-2 was examined by immunohistochemical staining. Results: 1) The HPV was detected in 6(19%) out of 32 cases. 2) The HPV 6/11 was dectected in 4 out of 21 cases of simple IP, HPV 16/18 in 1, HPV 31/33/35 in lout of 8 cases of IP with dysplasia respectively. 3) The positive expression of p53 was 13 cases out of 32 cases; 2 out of 21 cases of simple IP, all of 8 cases of IP with dysplasia and 3 cases of IP with squamous cell carcinoma 4) The positive expression of c-erbB-2 was in 24 out of 32 cases; 16 out of 21 cases of simple IP, 6 out of 8 cases of IP with dysplasia, 2 out of 3 cases of IP with squamous cell ca. 5) The recurrence of IP occurred in lout of 6 cases of positive for HPV, in 4 out of 26 cases negative for HPV. 6) The recurrence of IP occurred only in positive cases for p53. 7) The recurrence of IP occurred in 4(17%) out of 24 cases positive for c-erbB-2, in 1(13%) out of 8 cases negative for c-erbB-2. Conclusion: The p53 expression was associated with Inverted papillomas exhibiting evidence of malignant transformation. Also, there was a correlation between the p53 expression and recurrence.