In this paper, I consider how trust affects the decisions of men who have sex with men (MSM) around using pre-exposure prophylaxis (PrEP) as HIV prevention in their sexual and romantic relationships, and how the use of PrEP affects their relationships with healthcare providers. MSM have to trust their sexual and romantic partners as well as their healthcare providers for PrEP to be successful as a relatively new HIV prevention strategy. This trust includes both interpersonal trust and institutional trust and (...) it is complicated by different kinds of relationship dynamics and the history of prejudice against MSM in healthcare institutions. (shrink)