The aim of the present survey was to assess the caries prevalence in schoolchildren of the city of Winterthur in the year 2002. A simple random sample of 1000 schoolchildren was drawn. 65% of the children participated in the standardized investigation. The mean DMFT-value (permanent dentition) in 12-year-olds was 1.0 and was on a low level in a European comparison. The mean dmft-value (deciduous dentition) in 7-year-olds was 2.0. From 1971 to 2002, DMFT-values decreased by about 80% in Winterthur. The dmft-values decreased by about 60%. The splitting by nationality revealed a high caries prevalence in schoolchildren from the former Yugoslavia and Albania. A multivariate analysis showed no significant differences in caries prevalence between the schoolchildren of the city of Winterthur and other communities of the canton of Zurich.