The aim of the study was to examine the prevalence of dental caries in 4-year-olds in the town of Umeå in 1987, and compare that data with data from 4-year-olds examined in 1967, 1971, 1976 and 1980/81, using the same diagnostic methods and criteria. The reduction in the mean dmfs value amounting to 75% between 1967 and 1980/81 did not continue up to 1987, but there was an increase in the number of children without caries from 50% in 1980/81 to 58% in 1987. There was also an increase in the proportion of children with 10 or more dmf-surfaces during the same period. The mean value for dmfs remained the same in these years. An analysis was made of the correlation between the frequency of tooth-brushing, use of fluoride toothpaste, snack consumption and the dmfs-value in 1987. A statistically significant difference in mean values for dmfs was found between children who had their teeth brushed greater than or equal to 2/day and less than or equal to 1/day. When fluoride toothpaste was used, the difference was less pronounced. There was no statistically significant difference in the mean intake frequency of snack products among children with and without caries, but a higher proportion of caries-free children was found among those with a low intake frequency of such products.