Objective — The prevalence, and attitudinal predictors, of sexual aggression were examined in a non-forensic sample of South African high school males. Method — Survey questionnaires were administered to 446 males (aged 16 to 25 years) attending schools in the greater Durban area, South Africa. Results — A history of sexually aggressive behaviour was reported by 66.8% of respondents, with 17.5% reporting an act of sexual aggression that met the legal definition of rape or attempted rape. A multivariate analysis of variance indicated a significant relationship between sexually abusive behaviour and attitudes supportive of both sexual and physical aggression. Additionally, a tendency to attribute blame to the victim of sexual aggression and attitudes reflecting an internalised culture of violence significantly discriminated between respondents who committed rape/attempted rape, indecent assault, and crimen injuria. Conclusions — These findings indicate relatively high rates of sexual offending among South African high school males and suggest that primary prevention programmes are likely to be most effective if they target attitudes supportive of both sexual and physical violence.