Prostitution has always been a sensitive issue for national legislators in charge of enacting laws either to regulate or ban this activity. Whereas in some countries the decision has been made to treat prostitution as a normal activity subject to regulations, prostitution is, in other countries, banned. Regardless of the legal status of prostitution in a given country, the activity may amount to trafficking in human beings for the purpose of sexual exploitation if all constitutive elements of the offence are present. Indeed, traffickers may circumvent national rules regulating prostitution and offer sexual services outside the legal framework designed by the legislator. They may also, in countries where prostitution is not allowed, find loopholes and alternatives in order to illegally offer sexual services. Considering that trafficking in human beings constitutes a serious criminal threat, and its victims suffer from serious violations of their human rights, efforts are required not only to protect its victims and prosecute its perpetrators, but also to prevent it. The present contribution will focus on a specific aspect of its prevention: the issue of demand for sexual services and how to address it. The national policies and laws on prostitution may have an impact on such demand, as for instance when in some countries, the criminalisation of the use of sexual services might dissuade potential clients from having recourse to such services. However, determining how to best address demand for sexual services remains a highly sensitive issue. In the absence of strong obligations at international or European levels, national legislators benefit from a large margin of discretion. With the aim of partially filling the gap in research about this issue, the two authors provide a comparative analysis of national legislations in selected countries, and present preliminary conclusions on the impact of legislation and policies on prostitution on the prevalence of trafficking in human beings.