This article addresses the relationship between sexual risk behaviour and contraceptive behaviour, and considers whether adolescents who use condoms are practising birth control or STD protective behaviour. The material comprised a representative sample of 3000 Norwegians aged 17-19 years. Data were collected by anonymous self-administered questionnaires. The response-rate was 63%. At the first sexual intercourse 51% of the adolescents used condoms and 7% birth control pills. At the most recent intercourse 31% used condoms and 38% the pill. Use of the pill was widespread among adolescents with high coital frequency and few coital partners. Use of condoms was not particularly widespread among adolescents who reported a relatively large number of coital partners. Irrespective of the number of years they had been coitally active there was no significant difference between those who intended to use condoms at the next sexual intercourse and those who did not as regards their beliefs about condoms as protection against STDs, HIV and unintended pregnancies. The results from this study indicate that the majority of adolescents who use contraception do this for protection against unintended pregnancy and not for protection against STDs. The preference for the pill may make teenagers less prepared to practise STD protective behaviour in specific situations.