Objective: To assess current and intended future use of pre-exposure prophylaxis (PrEP) among men who have sex with men (MSM) and characterise those attending sexual health clinics, the anticipated PrEP delivery setting. Design: Cross-sectional study. Methods: Self-administered survey of 842 HIV negative MSM recruited from social venues in London in 2011. Results: One in 10 (10.2%, 83/814, 95% CI 8.2% to 12.5%) and one in 50 (2.1%, 17/809, 95% CI 1.2% to 3.3%) reported having ever used post-exposure prophylaxis (PEP) and PrEP respectively. Half reported they would be likely to use PrEP if it became available as a daily pill (50.3%, 386/786, 95% CI 46.7% to 53.9%). MSM were more likely to consider future PrEP use if they were <35 years (adjusted OR (AOR) 1.57, 95% CI 1.16 to 2.14), had unprotected anal intercourse with casual partners (AOR 1.70, 95% CI 1.13 to 2.56), and had previously used PEP (AOR 1.94, 95% CI 1.17 to 3.24). Over half of MSM (54.8% 457/834 95% CI 51.3 to 58.2) attended a sexual health clinic the previous year. Independent factors associated with attendance were age <35 (AOR 2.29, 95% CI 1.68 to 3.13), and ≥10 anal sex partners in the last year (AOR 2.49, 95% CI 1.77 to 3.52). Conclusions: The concept of PrEP for HIV prevention in the form of a daily pill is acceptable to half of sexually active MSM in London. MSM reporting higher risk behaviours attend sexual health clinics suggesting this is a suitable setting for PrEP delivery.