Assess willingness to use HIV pre-exposure prophylaxis (PrEP), support for others using it and willingness to have sex with partners using PrEP among Australian gay and bisexual men (GBM).National, online cross-sectional surveys of Australian GBM were conducted in 2011, 2013 and 2015. Scales measuring support for and willingness to have sex with men using PrEP were developed in 2015 using factor analysis. Trends and associations with key measures were analysed using multivariate logistic regression.During 2011-2015, 3850 surveys were completed by GBM. Willingness to use PrEP among HIV-negative and untested men did not change between 2011 (28.2%) and 2015 (31.7%, p=0.13). In 2015, willingness to use PrEP was independently associated with younger age, having an HIV-positive regular partner, recent condomless anal intercourse with casual male partners (CAIC), more than 10 male sex partners in the previous 6 months, ever having taken postexposure prophylaxis and having fewer concerns about using PrEP. In 2015, 54.5% of GBM supported other GBM taking PrEP and 39% were willing to have sex with men using PrEP. Support for and willingness to have sex with PrEP users were both associated with being HIV-positive, having a university degree and having two or more male partners in the previous 6 months. Willingness to have sex with men on PrEP was also associated with recent CAIC and using party drugs for sex, but was less likely among men who consistently used or had a positive experience using condoms.Interest in and support for using PrEP are concentrated among men who engage in higher risk practices and who know more about living with HIV. This is consistent with the targeting of PrEP in Australia.