The papilloma of the larynx is usually divided into juvenile and adult group by age of onset because of different clinical course. It may be characterized by relentless recurrence in spite of appropriate therapy. Accordingly, many have investigated factors related to clinical behavior and relentless recurrence. The aim of this study is to search for the factors related to recurrence using histopathological lectin histochemical study and in-situ DNA hybridization. The results of this study are as follows : 1) Atypia was more predominant and cellular keratinization was a little more frequently observed in recurrence group. 2) In the lectin histochemical study, there were changes in response of PNA between recurrence and non recurrence group, and WGA or RCA-1 showed different responses. Both groups showed a negative reaction in SBA. 3) In the study of in-situ DNA hybridization, we have presented evidence for expression of papillomavirus, etiologically related to the relentless recurrence. Papillomavirus type 6/11 was isolated in 66.7% of the cases in recurrence group, but was not found in non-recurrence group. Therefore, from the above results cellular atypia is believed to be related to recurrence and latent infection of papillomavirus type 6/11 has important role in the clinical outcome of both recurrence and non-recurrence group.