Homeless, Anglo-Australian and Greek-Australian 16-year-olds were questioned about their sexual behaviour and sexual beliefs. Measures of sexual risk-taking included type of behaviour, condom use and number of partners. Drug risk was assessed by extent of i.v. drug use, and sharing and cleaning needles. Sexual beliefs included self-perceptions of sexual anxiety, arousal, exploration and commitment. In addition, motivations for engaging in, or avoiding, sex were elicited. The behaviour patterns of homeless adolescents placed them at considerable risk of HIV infection for both sexual and drug risk, and significantly more so than their home-based peers. Gender stereotypic self-perceptions were reported, and homeless and Anglo-Australian youths demonstrated a more masculine style in their self-perceptions than were Greek-Australians. Preferred motivations for sex differed, with homeless youths less concerned about the consequences of sex and more with self-gratification than the home-based adolescents. For homeless girls, higher levels of sexual risk were predicted by perceptions of greater arousal and by less concern about the consequences of sexual activity. Implications for targeted interventions are discussed.