The aim of the present study was to assess the changes in prevalence of early radiographic alveolar bone loss in a birth cohort (all subjects born 1970) over a period of 8 years as related to sex, ethnic origin, orthodontic treatment and socio-economic status. In 1984, the target population consisted of 2767 subjects. In 1986, 1988 and 1992, sets of bite-wing radiographs were obtained from samples of the same population. Alveolar bone loss was recorded if the distance from the cemento-enamel junction to the alveolar crest exceeded 2 mm measured on posterior bite-wing radiographs. The frequency of subjects with radiographic alveolar bone loss increased significantly with age (p