The aim of this study was to investigate the knowledge of and attitudes to oral health among 12- and 15-year-old students in Sweden. The results are designed to act as a baseline survey to evaluate future interventions. From all 85 schools in the County of Uppsala, ten schools were randomly selected. In all, 993 students were offered the chance to participate in the study. 793 (8o%) individuals answered a questionnaire consisted of fifteen structured questions about their knowledge and attitudes to oral health. The result showed that the level of knowledge by adolescents is relatively high. A large majority of the subjects felt that their teeth were important. Most of the adolescents had learned about oral health from the dental team. With the exception of the question about the meaning of the word "periodontitis", all the questions produced a distribution of correct answers in favour of the girls. Older students showed more knowledge compared with younger students. In none of the questions did the younger students display more knowledge than the older. The adolescents with an immigrant background showed less knowledge compared with natives of Sweden in several areas. Despite having less knowledge of oral health, more students with an immigrant background than natives of Sweden stated that their teeth were important. Several of the survey questions call for answers in the form of factual knowledge. Knowledge is therefore regarded as a quantitative measure of a reproduction, where the adolescents are expected to reproduce something that they have already learned. Increasing criticism has been levelled against this view of knowledge. Facts are not enough to induce young people to change their health behaviour. Facts are an important part of the message but must be complemented by reflection and consideration of how the receiver understands it.