Background The aim of this study is to describe homosexual experience and characteristics of recent homosexual encounters among Australian adults and identify changes between 2001-02 and 2012-13. Computer-assisted telephone interviews were completed by a representative sample of 20094 men and women aged 16-69 years and the participation rate among eligible people was 66.2%. Respondents indicated the number of same-sex partners they had had in their lifetime and in the last 12 months. Those who reported any homosexual experience were asked the age at which this first occurred and about characteristics of the first and most recent homosexual encounter. Reporting ever having same-sex experience was more common in women (13.5%) than in men (6.5%, P<0.001). Among these people, men reported more lifetime and recent same-sex partners than women (P<0.001). Same-sex experience was associated with some but not all indices of higher socioeconomic status. In men, it was associated with living in a major city (P=0.02) and in women, it was associated with younger (<30 years) age and with very low income (P<0.001). Men were younger than women at their first homosexual encounter (P=0.005). Women were more likely than men to have their first same-sex encounter with a regular partner. For women but not men, there was a significant increase in the proportion reporting same-sex experience since 2001-02. Same-sex experience is not uncommon and is increasing in prevalence in young Australian women. The high number of same-sex partners among homosexual and bisexual men places them at greater risk of sexually transmissible infection.