Young people in sub-Saharan Africa are identified as vulnerable to HIV infection; their vulnerability is attributed to risky sexual behaviours, low risk perceptions, and lack of access to HIV information. Very few studies, however, have linked perceptions of HIV/AIDS risks and knowledge about AIDS to sexual behaviours of youth in Ghana. Using the 1998 Ghana Demographic and Health Survey, this paper explores whether knowledge and perceptions of HIV/AIDS risk inform the sexual behaviours of never-married youth aged 15 to 24 years. We also assess whether such perceptions vary between females and males. From a policy perspective, understanding this link may be crucial to checking the further spread of HIV/AIDS