In most Swedish counties, epidemiological data on the permanent dentition are collected on patients between 7 and 19 years of age. However, for the primary dentition, epidemiological data are only available for the 3-6-year-old age groups. As far as we know, no studies have investigated the relation between caries prevalence in the early primary dentition and caries prevalence or treatment performed in the late primary dentition. Thus, the purpose of the present study was to investigate the relationship between dental treatment in the primary dentition of Swedish children 7-12 years of age and caries experience in the primary dentition at 6 years of age. This retrospective study is based on record data from a randomly selected sample comprising 10% of all children born in 1987 in Jönköping County (n=433). Of these children, 381 had been treated regularly at the Public Dental Service clinics between 7 and 12 years of age and were included in the study. It was found that children with previous caries experience at 6 years of age received significantly more treatment during the studied period compared to children who were caries free at the same age. The children with caries experience required a mean of 3.5 times more treatments compared to caries-free children. The present study underlines the importance of early detection and prevention of caries in the primary dentition if optimal dental health is to be expected in the late primary dentition.