In 2003 the project Changes in oral health and preventive behaviour was carried out for the sixth time in succession in the Netherlands. Children and adolescents were asked to fill out a questionnaire and to participate in an oral health examination. Compared to the 1996/1997 results 9-year-olds had a lower incidence of FS and DMFS, 14-year-olds had a higher incidence of DS, and 20-year-olds had a larger number of DS and a smaller number of FS, DMFS and DMFT in 2003. The care index in 2003 was between 48% and 68%. Compared to the 1996/1997 results more 21-year olds visited the dentist annually instead of twice a year. Considering possible consequences of the change in the Dutch health insurance system as of January 2006, such tendencies need careful monitoring.