It is well known that laryngeal papilloma has a tendency for malignant transformation, but the incidence was variable among many authors. The authors present a case of laryngeal cancer which was considered to be transformed from laryngeal papilloma after six years follow up, with serial pathological review of the specimen. Incidence of malignant transformation in our hospital is 2.5% of total laryngeal papilloma and it is the only case among 57 laryngeal cancer for 6 years duration. It must be stressed that long term follow up is recommanded in adult type laryngeal papilloma.