Health education is a part of the primary school science curriculum in France. Teachersoften consider sexuality education and sexually transmitted diseases prevention as a topic they cannotteach without the help of partners. This paper is an account of a research carried out to study the representationsof primary school pupils (Key Stage 2, French children, fmtn 94 1 ) about HIV/AIDS and toanalyse the impact of an educational programme on these reinrsentations. The programme was based ona socio-constructivist approach to learning It aimed to modih pupils' representations through regularteacher's activities and interventions ty health educators. The resulis indicate that after the intervention,pupils' scientific knowledge was more precise, and communication about HIV/AIDS between members ofthe family improved. The representations shifted from a sense of powerlessness and fatality towards asense of Ow possibility of acting to forestall injection. Nevertheless, the impact of the intervention wasweaker on underprivileged pupils