Background:
Adults with male and female sex partners have riskier sexual behaviors than those with opposite-sex partners. Little is known about the prevalence of same-sex partners and associated sexual risk-taking among adolescents; to maximize samples, those reporting partners of both sexes and only same-sex partners have often been combined.

Objective:
We describe sex of partners, demographics, sexual risk behaviors, and sexual identity in a population-based sample of in-school adolescents.

Method:
Sexually experienced respondents to the 2005 NYC Youth Risk Behavior Survey who reported the sex of lifetime sexual contacts were categorized into mutually exclusive heterosexual (only opposite-sex partners), homosexual (only same-sex partners), and bisexual (same- and opposite-sex partners) subgroups. Prevalence of sex of partner(s) and risk behaviors was estimated. Identity distribution (straight, gay/lesbian, bisexual, unsure) was examined.

Result:
Of 1881 males and 1705 females, equal numbers of males (~3%) and females (~3%) reported homosexual behavior, but more females than males reported bisexual behavior (9% vs. 3%, p<.001). More bisexual (83%) than heterosexual (46%, p=0.0003) and homosexual (28%, p<0.0001) males reported >2 partners in 3 months. Most bisexual males (72%) reported no condom use at last sex, versus 21% heterosexual and 23% homosexual males. Homosexual males and females had a lower prevalence of multiple lifetime partners, intimate partner violence history, and forced sex history than bisexuals or heterosexuals. Many homosexual/bisexual adolescents (32% of males, 40% of females) self-identified as straight.

Conclusion:
Of NYC adolescents, 18% report a same-sex partner, a higher estimate than other published rates. Given a substantial community prevalence of STD, bisexual youth exhibit behaviors that place them at high risk.

Implications:
Pediatricians/school health providers must inquire about behaviors, not identity, to assess STD/HIV risk. Schools should provide referral information for STD/HIV screening. Health education should be appropriate for youth with same-sex partners. The evolution of sexual risk-taking among exclusively homosexual adolescents is of interest.