This phase III, multi-centre, comparative, double-blind, randomized trial on 2 parallel groups is designed to evaluate a strategy for the prevention of HIV infection including "on demand" antiretroviral pre-exposure with Truvada versus placebo, associated with overall prevention (counselling, condoms, sexually transmitted diseases (STD) screening, hepatitis B virus (HBV) and hepatitis A virus (HAV) vaccinations and post-exposure treatment of HIV infection) in men who have sex with men (MSM), exposed to the risk of HIV infection. Indeed recent studies have reported a higher incidence of new HIV infection in MSM as compared to the general population, new approaches to the prevention of HIV infection are, therefore, necessary in order to consider the limits of current strategies.