It is estimated that 750 people die daily from HIV/AIDS related complications in Kenya and that HIV infection among the youth is escalating at a phenomenal rate as evidenced by the 18% of the young people aged between 12-25 years who are infected, among them street-based adolescents. Many factors have been attributed to risky sexual behaviors: penetrative and receptive sexual contacts, unprotected sexual contacts, sex with multiple sexual partners and casual sexual partners. This study investigated the association between the street-based adolescents’ level of HIV/AIDS awareness and their HIV-related sexual risk-taking behaviors. Quantitative and qualitative techniques were employed for data collection. A total sample of 150 street-based adolescents aged between 12 and 25 years in the Nairobi City Councils’ rehabilitation centers were surveyed. The study indicates that awareness levels were high among the street-based adolescents 99.3 %(149) although myths and misconceptions about HIV/AIDS transmission modes still abound. These included the belief that HIV/AIDS can be transmitted through ‘sharing a meal with an infected person’ 12.7%(19), ‘living with an infected person in the same apartment’ 10.7%(16), ‘sharing of toilets and bathrooms with an infected person’ 15.3%(23), ‘working with an infected person’ 6.7%(10) and by ‘shaking hands with an infected person’ 3.3%(5). Majority of the adolescents i.e. 52.7% (79) [43.4% (36) male; 64.2 %(43) female] thought that they were at risk of contracting HIV/AIDS, while the others 47.3%(71) [56.6%(47) male; 35.8%(24) female] thought they were not. Another 20.7%(31), 21.3%(32), 16%(24), and 34%(51) respectively considered their degrees of contracting HIV/AIDS as very likely, somewhat likely, somewhat unlikely, and very unlikely. It is important therefore that Information Education and Communication (IEC) and Behavior Change Communication Intervention (BCCI) campaigns are targeted at street-based adolescents since, misconceptions about HIV/AIDS have been shown to lead to wrong selfperceptions of risk from HIV/AIDS thereby hampering efforts aimed against this world’s most devastating pandemi