Men with histories of both homosexual contact and injecting drug use (IDU) are at increased risk of HIV infection over men who have only one such risk. Despite this, their special needs and circumstances have been neglected by AIDS prevention programmes. A survey of a wide spectrum of homosexual male IDUs was carried out in Melbourne and Sydney in 1993 to inform the development of specific policy and programmes for HIV prevention in these subcultures. Of 169 men, self-reported HIV prevalence was 27%. Decreasing compliance with safe sex guidelines (as measured by numbers of casual partners, participation in anal intercourse and use of condoms) was associated with HIV seropositivity, increased age, and increased participation in sex work; having a regular male partner was not protective against unsafe sexual behaviour, no matter the length of the relationship. A substantial proportion (15%) reported inconsistent condom use during anal sex with more than two partners in the preceding month: they were slightly more likely to be engaging in sex work, less 'stable' and more likely to be HIV infected. Sexual risk was not strongly associated with unsafe injecting, which was in general safe. Men who both have homosexual sex and inject drugs are groups at high risk of HIV, more from unsafe sex than from shared injecting equipment; men who believed themselves to be HIV infected were continuing to have sex in such a way that would allow transmission. These are clearly groups in need of priority targeted interventions.