Risky sexual behaviour is one of the major concerns in South Africa today. It is important to understand the socio-cultural, as well as behavioural factors that are associated with such sexual problems. The aim of the study was to explore the socio-cultural influences in decision making involving sexual behaviour among adolescents in Khayelitsha, Cape Town. Social influences such as peer influence, low socio-economic status, alcohol use and lack of parental supervision were found to play a role in adolescents’ risky sexual behaviour. Cultural beliefs, cultural myths and social norms were identified as socio-cultural influences that endorsed issues such as gender disparities, which made adolescent mothers vulnerable. These findings point out the need to prioritize adolescents in intervention programmes in environments such as school, church, at home and community at large with emphasis on awareness and enrich adolescents’ knowledge on prevention of both HIV/AIDS and unplanned pregnancies. Emphasis should be on changing cultural beliefs and norms that disapprovingly influence adolescents’ sexual behaviour.