OBJECTIVE: To consider the extent to which those presenting for post-exposure prophylaxis (PEP) after sexual risk had been encouraged to do so by their PEP-aware partners with (diagnosed) HIV. METHOD: Thirty men who had completed the 2005 UK Gay Men's Sex Survey who said they had ever tried to get PEP took part in a 30 minute telephone interview. RESULTS: Fifteen men in the sample described a sexual exposure incident where they had knowledge that their partner was diagnosed with having HIV. Of these, only five knew about their partner's HIV diagnosis prior to sexual contact. The remaining 10 sought PEP because their sexual partner revealed his positive status following potential sexual exposure. CONCLUSION: Our analysis revealed that word of mouth from friends, sexual partners and health professionals played a key role in men's knowledge about the existence of PEP. It is important for HIV and sexual health specialists to ensure that PEP information is not only targeted at those who are tested negative for HIV or are untested but also to people with diagnosed HIV.