In cross-sectional studies conducted in 1967, 1971, 1976, 1980, 1987, 1992, 1997 and 2002, 4-year-old children in Umeå, a city in northern Sweden, were examined for dental caries and background factors such as oral hygiene habits, use of fluorides, and sugar consumption. The same methods and criteria have been used in each of the studies from 1967 to 2002. The number of children with caries had declined from 87% in 1967 to 42% in 1987, but then the decline levelled out. In 2002, 46% of the children had caries with a mean dmfs value of 2.0 +/- 3.6. Six percent of the children had 10 or more dmfs. Immigrant children had a higher caries prevalence (p