Lifetime sexual behaviors were examined among 206 male and female runaway adolescents aged 11–18 in New York City who were predominantly Black or Hispanic. Most youths experienced oral, anal or vaginal sex with opposite‐sex partners (84%), began to engage in these heterosexual activities at a relatively young age (M= 12.9 years), and used condoms inconsistently or not at all (56%). Among sexually active youths, males initiated heterosexual activity at a significantly earlier age than females, reported more opposite‐sex partners, and had a higher prevalence rate of trading sex for money or drugs. These findings indicate specific areas for targeting AIDS prevention programs for runaway youths.