All patients treated for laryngeal papillomas with adult onset in the Copenhagen region during a 4-year period were identified for this epidemiological study. The incidence was 0.8/100,000 among the population at risk and the prevalence was 2.3/100,000. It is concluded that papillomas with juvenile and adult onset are one and the same disease and that single papillomas versus multiple papillomas cannot be considered different entities. As is the case with juvenile laryngeal papillomas, the prognosis is good and the morbidity low in most cases of adult onset papillomas, but malignant degeneration must be considered a risk factor.