The incidence rate of laryngeal papillomas in a Danish subpopulation (approximately 2.8 million inhabitants) was 3.84 x 10(-6) per year in the period 1968-1984. For juvenile papillomas the incidence rate was 3.62 x 10(-6), compared with 3.94 x 10(-6) for laryngeal papillomas of adult onset. When comparing different time periods a significantly low incidence was found in the time 1965-1968, while the incidence remained constant in 1969-1984. The low incidence rate in the early period may be real, but selectional bias may have played a part. It is general anticipated that maternal genital HPV-infections may serve as an HPV-reservoir, and that juvenile laryngeal papillomas is a result of HPV transmission from the mother to the child during birth. In the period in question cervical HPV-infections have been recorded with increasing frequency in younger women, indicating that the prevalence is rising. However, this is not reflected in the incidence of laryngeal papillomas.