The aim of this study was to investigate the knowledge of caries and gingivitis among third to fifth grade school children. A questionnaire was distributed to 117 children of a primary school in the south of Sweden. The result of the study indicate that the children had good knowledge regarding development and prevention of caries and gingivitis. However, the children did not know the meaning of the words caries and gingivitis. The children also appeared to lack important information about dietary measures to achieve good dental health.