Background To explore the long-term sexual health implications for gay men having first anal intercourse (FAI) at an early age.

Methods A nationwide online survey was conducted among 854 Australian gay men born between 1944 and 1993 (16–65 years).

Results Age at FAI dropped sharply from a median of 35 years among men born 1944–1953 to 18 years among men born 1984–1993. At their most recent sexual encounter, men who reported FAI at age 16 years or younger were more than twice as likely to have had receptive anal intercourse or reciprocal anal intercourse (both insertive and receptive in the same sexual encounter), and were almost twice as likely to report having more than 10 sexual partners in the past year. These men were also nearly twice as likely to have become HIV-positive since their sexual debut and were several times as likely to report having had a hepatitis A or C diagnosis. Additional features of the sexual health and behaviour of gay men who report early FAI will be presented that further demonstrate a need to pay close attention to age at FAI.

Conclusions Gay men who report early FAI are at higher risk of HIV than those who report later FAI, and are more likely to have recently engaged in risky sexual behaviour. Discussion will focus on explaining these patterns and why health service providers need to pay attention to age at FAI.