Understanding prior knowledge and experience with pre-exposure prophylaxis (PrEP) among men who have sex with men (MSM) is critical to its implementation. In fall 2011, NYC MSM were recruited via banner advertisements on six popular dating websites and asked questions about their knowledge and use of PrEP (n = 329). Overall, 123 (38%) respondents reported knowledge of PrEP, of whom two (1.5%) reported PrEP use in the past 6 months. Knowledge of PrEP was associated with high educational attainment, gay identity and recent HIV testing, suggesting an uneven dissemination of information about PrEP and missed opportunities for education. To avoid disparities in use during scale-up, MSM should be provided with additional information about PrEP.