A prospective study of 94 Dutch adults who have casual sexual partners examined whether two important aspects of safe sex. namely bringing up condom use (BCU) and actual condom use (ACU) are intentional or habitual. For each of these aspects, a model based on the Theory of Planned Behaviour (TPB: Ajzen, 1991) was pitted against a similar model that was extended with a path from past to later BCU and ACU, respectively. The results suggest that bringing up the issue of condom use was equally predicted by intentions and pat BCU. However, among people with casual partners. using condoms - and more importantly not using condoms - was especially predicted by past ACU, Suggesting a strong habitual component. These results are discussed in terms of their implications for safe sex education and the use of theories in safe sex promotion campaigns.