The WHO concluded in a report in 1994 that there is “clear evidence that regular, low-level exposure to fluoride can reduce caries prevalence”. The dominant community-based strategies for preventing dental caries are water fluoridation and salt fluoridation. The WHO recommends salt fluoridation as an alternative to community water fluoridation. OBJECTIVES: The aim of this study was to compare dental caries levels of schoolchildren with fluoridated domestic water supplies (ROI) with those using fluoridated salt (Germany) stratified by using an international social class schema. METHODS: A trained and calibrated dentist examined a representative, random sample of 350 twelve-year old children in Dublin (ROI) and Freiburg (Germany). A two stage sampling method was used. Dental caries was recorded using WHO criteria. The dental caries scores were stratified by using the Goldthorpe Social Class Schema. RESULTS: A total of 697 twelve-year old children were clinically examined, 376 were children in Dublin whose domestic water supply had been fluoridated since birth, and in Freiburg 321 who regularly used fluoridated salt. For Dublin the mean DMFT in social class 1 (highest social class) was 0.28, in social class 2 (medium social class) was 1.1 and in social class 3 (lowest social class) was 0.94. For Freiburg the mean DMFT in social class 1 was 0.31, in social class 2 was 0.61 and in social class 3 was 1.33. CONCLUSION: Caries levels in permanent teeth were significant lower amongst children in social class 1 in both cities. The caries levels showed a reduced disparity between children in social class 2 and 3 whose domestic water supply had been fluoridated since birth compared with those in social class 2 and 3 who had consumed fluoridated salt. The findings suggest that compared with salt fluoridation, water fluoridation may produce a greater reduction in socio-economic dental health inequalities.