Background Research documents substantial adolescent health disparities by sexual orientation, but studies are confined to a small number of countries—chiefly the USA. We provide first-time evidence of associations between sexual orientation and adolescent health/well-being in a new country—Australia. We also add to knowledge by examining health/well-being outcomes not previously analysed in national samples, considering adolescents reporting no sexual attractions, and rank-ordering sexual-orientation health disparities by magnitude.

Methods Data from an Australian national probability sample of 14/15 years old (Longitudinal Study of Australian Children, n=3318) and regression models adjusted for confounding and for multiple comparisons were used to examine the associations between sexual attraction and 30 outcomes spanning multiple domains of health/well-being—including socio-emotional functioning, health-related quality of life, depressive symptoms, health-related behaviours, social support, self-harm, suicidality, victimisation, self-concept, school belonging and global health/well-being assessments.

Results Lesbian, gay, bisexual and questioning adolescents displayed significantly worse health/well-being than their heterosexual peers in all outcomes (p<0.05). The magnitude of the disparities ranged between 0.13 and 0.75 SD, and was largest in the domains of self-harm, suicidality, peer problems and emotional problems. There were fewer differences between the heterosexual and no-attraction groups. Worse outcomes were observed among both-sex-attracted adolescents compared with same-sex-attracted adolescents, and sexual-minority girls compared with sexual-minority boys.

Conclusions Consistent with the minority stress model and recent international scholarship, sexual-minority status is an important risk factor for poor adolescent health/well-being across domains in Australia. Interventions aimed at addressing sexual-orientation health disparities within Australian adolescent populations are urgently required.