With about one quarter of new human immunodeficiency virus (HIV) infections occuring in young people, there is an on-going debate regarding the role of social capital on youth sexual behaviour. Some studies have suggested that high levels of family and community social capital may act as protective factors that lessen the likelihood of negative consequences; while others have concluded that social capital may be a risk factor for risky sexual behaviour among youth. Using data from the Third National Communications Survey (2012) conducted in South Africa, we examined the relationship between perceptions of social capital and youth sexual behaviour measured by age at first sex and condom use among 3 399 males and females (aged between 16 and 24 years). We assessed community perceptions of social capital with questions that measured trust, social participation, and support. The Cox proportional hazards regression model was used to predict the risk for early sexual debut. Logistic regression was used to predict the odds of condom use. There was no association between perceptions of social capital and youth sexual behaviour. This work reveals that youth sexual behaviour in South Africa may be influenced by socio-economic characteristics, especially at the individual level.