This study of 400 Australian heterosexual adults compared attitudes to prostitution and risk behaviours of 34 male clients of female sex workers, with non-client men and women. Client males were more likely not to use condoms with casual partners for vaginal or anal intercourse, to have more sexual partners overall, and to use injecting drugs. Only three men admitted to unprotected sex with a prostitute, so that their risk behaviour occurred mostly in non-commercial casual sexual encounters. For men but not women, attitudes to prostitution showed small but significant relationships with sexual risk behaviour. Disapproval of prostitution and belief in the victim status of prostitutes was associated with lower HIV risk. It was concluded that the low rates of HIV infection for female prostitutes in Australia were related to good management on the part of the sex industry and the contours of the epidemiology of the disease in Australia rather than the responsible behaviour of clients.