This study is based on repeated interviews with twelve heterosexual female commercial sex workers (SWs) in Perth. These informants deploy, with various degrees of success, strategies to demarcate ‘work‐sex’, with its socially ascribed stigma, from ‘non‐work sex’. Such strategies inhibit the spread of HIV at work but, ironically, increase the risk of HIV transmission during non‐work sex. SWs recognise this risk and construct a variety of rationales to reduce their fear of contracting HIV and justify their strategies of demarcating work‐sex from non‐work sex. Efforts to reduce the risk of HIV infection among Perth SWs would seem to depend upon addressing not only these strategies of demarcation but these rationales in a supportive environment that recognises the creative complexities of their lives.