Background: This article examines the vulnerability of adolescents of Benin to HIV / AIDS. It seeks to understand the measures in which certain socio-demographic and contextual variables which operationalize vulnerability shed light on the situation of adolescents in Benin.Method: To test the basic hypothesis, we compared the descriptions of 15-19 and 20-24 years olds interviewed as part of the MICS-Benin-2014 survey through descriptive and explanatory analyzes.Results: Analyzes reveal that with the exception of adolescent girls living in the most disadvantaged areas, in-depth knowledge of the sexual transmission of HIV / AIDS is generally good among adolescents. However, socio-demographic differences are less marked in terms of knowledge of mother-to-child transmission of HIV. On the other hand, many adolescents who have been tested for HIV have little regard for the result. This behavior, which is linked to the level of education and to the department for both sexes and in addition to the standard of living for adolescent girls, gives an overview of gender disparities and the extent of the gaps in obligations towards them to reduce the HIV infection.Conclusion: Develop strategies to improve knowledge about HIV and reduce the stigma on testing.