Pre-exposure prophylaxis (PrEP) is a relatively new HIV prevention strategy that is changing the sexual cultures of men who have sex with men (MSM), and specifically gay, bisexual, and queer men. PrEP changes how MSM build and maintain sexual and romantic relationships, how they live in communities, and how they are viewed in society more broadly. I consider the social and political dimensions of using PrEP as HIV prevention among MSM in this chapter by focusing on the concepts of stigma, trust, and solidarity. Following a critical history of HIV prevention and AIDS activism, which helps establish the context for PrEP use today, I present a relational analysis of post-PrEP culture, including the effects of PrEP-related stigmas on MSM; the dynamics of trust in MSM relationships; and the role of solidarity in MSM communities. This chapter demonstrates that complex socio-political questions about PrEP are often overlooked in favour of standard medical concerns. Understanding the politics of PrEP is crucial for highlighting its most profound and ethically significant impacts on MSM.