The majority of Finnish adults have lost one, some or all of their teeth. The prosthetic replacement of missing teeth has thus been an important element of adult dental care. However, there have been no longitudinal studies focusing on the development of oral health among the Finnish adult population in terms of further tooth loss. A baseline sample from 1977-78 was selected from the city of Turku to represent the adult population aged 30 years and over. Ten years later, a follow-up examination was carried out on this baseline study group. A new sample of persons aged 30-39 years was also obtained to provide cross-sectional information, allowing comparisons between this study group and the youngest age-group of the 1977-78 study. In 1977-78, 52 per cent of all subjects had 20 or more remaining teeth. The mean number of missing teeth was 15.8 (SD 11.05) and the corresponding median 12 teeth. The number of missing teeth was on average higher in the older age-groups (P