Even in the 'era of treatment' successful HIV prevention remains an enormous challenge. This article argues that there is a need to pay more attention to sex and desire in the design of HIV prevention programmes. The paper highlights how perceived "dirty" issues, such as sex between men and anal intercourse between men and women, are often overlooked by HIV prevention programmes. It also explores how reasons why people may "choose" not to place themselves in safety by engaging in sexual conduct with a high risk of HIV infection are often not explored by researchers. The author calls for effective programmes that enable behaviour change. This means dealing openly and honestly with the lives that people actually lead and the sex they actually have. The need to ensure that researchers do not avoid asking difficult questions is also emphasised.