this study aimed to assess the effect of the dissemination of scientific knowledge on hiv / aids in three aspects: knowledge about the disease, attitudes toward condom use and social representation of aids risk. the research was carried out with high school students and consisted of two studies: one on receipt of an informational video (active and passive reception) and one on a simulated case of a scientific controversy. the results showed that the video information, in the condition of active reception, is effective in increasing knowledge, but does not affect participants' attitudes regarding condom use. in the simulated case there was a significant increase in scientific knowledge and a favorable attitude was generated on the part of students. as for the social representations of aids risk, this research showed independent effects on the activation of elements of these representations. in the active reception condition participants associated aids risk with sex and prevention; in the passive reception, with sex and risk behaviors; and in the simulated case, with sex, treatment and prevention. aids risk is represented by teenagers as a result of engaging in unprotected sex, since sex appears as a central element in the representation.