Aim: The aim of this study was to investigate oral health status and coherent determinants in children and adolescents with foreign background compared to children with Swedish background. Methods: In 1993 and 2003 cross-sectional studies with random samples of individuals in the age groups 3-,5-,10- and 15-years were performed in Jönköping, Sweden. All individuals were personally invited to a clinical and radiographic examination of oral health status. They were also asked about their attitudes and knowledge about teeth and oral health care habits. The final study cohort comprised 739 children and adolescents, 154 with Foreign background (F-cohort) and 585 with Swedish background (S-cohort). Results: Both in 1993 and 2003 more 3- and 5-year-olds in the S-cohort were caries-free compared to the F-cohort. In 1993 dfs/DFS was higher among 3- and 5-year-olds in the F-cohort (p=0.01). In 2003 dfs/DFS was significantly higher in all age groups in the F-cohort compared to the S-cohort. The cumulative percentage of proximal caries-free, initial and manifest lesions and restorations among 10-year-olds in the F-cohort were in 1993 55%, 23%, 4% and 18%. The corresponding figures for the S-cohort were 69%, 20%, 6% and 5%, respectively. In 2003 figures in the F-cohort were 54%, 29%, 4% and 13% compared to 82%, 12%, 1% and 5% in the S-cohort (p=0.037). Among males with foreign background and lived in families with low education, the odds was four times higher (OR=4.0 +95%CI; 2.2-7.2) to be exposed to dental caries, then among their Swedish counterparts. Conclusions: There had been a decline in caries prevalence between 1993 and 2003 in all age-groups except among the 3-year-olds. However the improvement of dfs/DFS was stronger in the S-cohort in all age-groups and the gap between the F- and S-cohorts was considerable larger in 2003 compared to 10 years earlier.