In 1984-85 a representative sample of 286 Danish women and 336 men aged 16-20 years were interviewed about their sexual debut. Seventy-four females (25.9%) and 101 males (30.1%) had not yet experienced sexual intercourse. A maximum likelihood estimation method was used to establish the age distribution at sexual debut. This takes into account knowledge of age at interview among the non-experienced respondents and of the few who did not report age at sexual debut. The median age at first sexual intercourse was close to 16.8 years for both females and males. This appeared to be a consequence of age at debut declining among women and remaining unchanged among males during the preceding 20 years.