U.N. peacekeeping missions succeed in preventing the resumption of conflict and saving lives. At the same time, a series of sexual exploitation and abuse scandals since the early 2000s has raised concerns about the conduct of peacekeepers. We examine a related, but generally overlooked, potential negative externality of peacekeeping missions: the forced trafficking of sex workers. We argue that U.N. peacekeepers increase demand for sex work and that this demand may be met through human trafficking for forced prostitution. Using data on U.N. peacekeeping missions between 2001 and 2011, we evaluate the effect of a peacekeeper presence on human sex trafficking in and around the host state. We find that the presence of U.N. peacekeeping forces correlates positively with a state being cited as a destination for forced prostitution. This has important implications for the future deployment of peacekeeping forces around the world.