Assess the acceptability of HIV treatment as prevention and early antiretroviral treatment among gay and bisexual men in Australia and any changes in attitudes over time.National, online, cross-sectional surveys of gay and bisexual men were repeated in 2011 and 2013. Changes in attitudes to HIV treatment over time were assessed with multivariate analysis of variance. The characteristics of men who agreed that HIV treatment prevented transmission and thought that early treatment was necessary were identified with multivariate logistic regression.In total, 2599 HIV-negative, untested and HIV-positive men participated (n = 1283 in 2011 and n = 1316 in 2013). Attitudes changed little between 2011 and 2013; most participants remained sceptical about the preventative benefits of HIV treatment. In 2013, only 2.6% of men agreed that HIV treatment prevented transmission; agreement was associated with being HIV-positive, having an HIV-positive regular partner, and having received HIV post-exposure prophylaxis. In contrast, 71.8% agreed that early antiretroviral treatment is necessary; younger men were more likely and HIV-positive men and participants with HIV-positive partners were much less likely to agree with this.Promoting the individual health benefits of HIV treatment rather than its preventative benefits remains more acceptable to Australian gay and bisexual men.