Gay men and lesbian women face various health inequities as well as disparate treatment from healthcare providers. Stereotypes around sexual health for gay people might contribute to these disparities. In four studies (N = 1658), we explored stereotypes about gay men and lesbian women’s sexual health and their implications in a healthcare context. In Studies 1 and 2, we found people explicitly and implicitly associated gay men with promiscuity and sexually transmitted infections to a greater degree than lesbian women, straight men or straight women. In Studies 3A and 3B, we tested these associations in the healthcare domain, finding that people express more prejudice and discrimination towards gay men and lesbian women with STIs versus those without STIs or straight counterparts with either type of disease. Taken together, the current research identifies some psychological factors that may underpin health disparities and healthcare barriers for gay and lesbian people.