Aims: To get a view of changes in caries experience of children and adults during the twentieth century a comparison was made between the available epidemiological data.Methods: Studies in children and adults were performed in The Hague in the years 1911-15 and throughout the country in the years 1941-45.Caries experience of adults was established furthermore in 1986 in a national study and in 1983 and 1995 in 's-Hertogenbosch.Since 1950 many studies were performed in children.For each period of fi ve years mean dmft-and DMFT-values were computed for 6-and 12year-old children respectively.Results: In 1911-15 in 6-year-olds a mean dmft of 2.8 was found, 33% had no caries in the deciduous dentition.The highest dmft number (9.1) for this age group was found in the period 1966-70, !1% were caries free in that time.Afterwards the mean dmft decreased to 1.8 and the number of caries free children increased to about 60%.For 12-year-old children the mean DMFT was 1.3 in 1911-15, increased to 8.0 in the period 1961-65 and decreased to 0.8 at the end of the century.In these years 37, 0.6 and 70% of the 12-year olds were caries free.For 25-39-year-olds the DMFT was 9.5 in 1911-15.The highest mean DMFT (18.1) was found in 1983.In 1995 it decreased to 14.4.For 1911-15 the percentages of caries free persons in this age category is unknown; it was !1% in 1941-45, 1983 and 1986 and 1.1% in 1995.In conclusion, at the end of the century caries experience of 6-and 12-year-old children was lower than at the beginning.For aduts the opposite is valid.