The paper discusses factors associated with sexual risk behaviour, i.e. failure to use condoms consistently during sexual intercourse, among unmarried sexually experienced youths in South Africa. Data from the ‘Transitions to Adulthood in the Context of AIDS in South Africa’ surveys of 1999 and 2001 were analysed to identify factors associated with high sexual risk behaviour among the youth. The multinomial regression models for male and female youths were fitted separately for the 1999 and 2001 data sets. The results show increasingly consistent use of condoms during sexual intercourse and that high sexual risk behaviour among youths is predominantly determined by social factors such as ‘ever-pregnant’ or ‘ever made pregnant’, ‘ever given something for sex’, age of sexual partner, currently in school, pressured by friends to have sex, peer influence on safe sex and education level for males. There is evidence that availability of contraception information is important in strategic interventions that seek to change the sexual behaviour of the youth in South Africa.