OBJECTIVE: The aim of this article was to examine the relationship between childhood caries, body mass index (BMI) and subsequent changes in BMI over 6 years, and to investigate whether these associations were modified by social class. METHODS: Data were from the European Youth Heart Study (EYHS) merged with data on caries experience from the Danish National Board of Health, (SCOR register). RESULTS: At baseline, 26.2% of the children/adolescents were caries free and 39% at follow-up. A larger percentage of normal weight children/adolescents were caries free, compared with the overweight/obese group of children/adolescents. The linear regression analysis showed that childhood caries was generally not associated with either BMI or subsequent changes in BMI. However, among children whose mothers were well educated, there was an inverse association between caries at baseline and subsequent changes in BMI over a period of 6 years, for example, a high caries experience was associated with a smaller increment in BMI, compared with the group of children with a low caries experience. No association was found for those with lower SES. CONCLUSION: An inverse association between caries and subsequent changes in BMI was found, but only among children with well-educated mothers, suggesting that high caries experience may be a marker for low future risk of overweight among the more advantaged. Associations did not appear to be significant among the less advantaged; however, numbers in this group were low, and an association may have been overlooked. Hence, more studies are needed to confirm these findings.