The etiology of inverted papilloma(IP) remains unknown, but several studies have reported that Human Papillomavirus(HPV) may play a role in the pathogensis of sinonasal inverted papilloma(IP). And recent reports demonstrate the possible etiologic role of Epstein-Barr virus (EBV) in sinonasal IP. The aim of this study is to detect HPV and EBV in sinonasal IP, to examine the relationship between HPV subtype and sinonasal IP, to investigate the relation between HPV and EBV. We reviewed 30 cases of sinonasal IP(simple IP 19 cases, IP with dysplasia 8 cases, IP with squamous cell carcinoma 3 cases). Paraffin embedded archival tissue was used in this study. Detection of HPV, EBV were examined by in situ hybridization(ISH) using HPV type 6/11, 16/18, 31/33/35 DNA probe and EBER probe. The HPV was detected in 6(20%) out of 30 cases. The HPV 6/11 was dectected in 4 out of 19 cases of simple IP, HPV 16/18 in 1, HPV 31/33/35 in 1 out of 8 cases of IP with dysplasia respectively. The EBV was not detected in 30 cases. HPV may play a role in the pathogensis of sinonasal inverted papilloma. But EBV is not a etiopathologic factor to be considered in the development of sinonasal IP.