Samkange-Zeeb et al. BMC Public Health 2011, 11:727 http://www.biomedcentral.com/1471-2458/11/727 The representativeness of study participants in some studies could not be assessed as it was not mentioned how the schools were selected [37,40-44,49]. Different socioeconomic environments of individual schools are likely to affect results, but there is currently not suffi- cient information to assess this. The school setting offers an effective way to access adolescent populations universally, comprehensively and uniformly [56]. It plays an important role for sex educa- tion, especially for those adolescents with no other information sources. Furthermore, some parents are not comfortable discussing sexual issues with their children. It therefore comes as no surprise that many young peo- ple cite the school as an important source of informa- tion about sexually transmitted diseases [26,27]. Although sex education is part of the school curriculum in many European countries, there are differences in the issues focused on. In some countries sex education is integrated in life skills approach, whilst biological issues are predominant in others and at times the focus is on HIV/AIDS prevention [57]. Generally it seems that edu- cation schedules offer a range of opportunities to raise knowledge and awareness of STD among adolescents. Conclusion In general, the studies reported similar low levels of knowledge and awareness of sexually transmitted diseases, with the exception of HIV/AIDS. Although, as shown by some of the findings on condom use, knowledge does not always translate into behaviour change, adolescents’ sex education is important for STD prevention, and the school setting plays an important role. Beyond HIV/AIDS, atten- tion should be paid to infections such as chlamydia, gonorrhoea and syphilis. Additional material Additional file 1: Review Protocol: The preparation process for the systematic review is documented in the file. Included are the objectives of the review, inclusion and exclusion criteria, the search strategy, definition of outcomes, as well as the data abstraction table. Authors’ contributions FSZ developed the concept for the study, conducted the literature search, assessed studies for inclusion in the review and extracted data. She also prepared drafts and undertook edits. LS was involved in the development of the study concept, conducted the literature search, assessed studies for inclusion in the review and extracted data. HZ was involved in the development of the study concept. All authors contributed to the editing of the drafts and have read and approved all versions of the manuscript. Competing interests The authors declare that they have no competing interests. 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