This article discusses the implementation of duties to reduce the market for sexual services of trafficked persons, both adults and children. The article begins by describing the duties that stem from international and European obligations. It then presents the legislation and practice of five European states (Hungary, Italy, the Netherlands, Sweden and the United Kingdom) regarding human trafficking and the purchase of sexual acts from trafficking victims. The states in the study have introduced measures to combat human trafficking by effective prosecutions and sentencing of traffickers. They have, however, taken few measures to combat demand for the sexual services of trafficked persons; in some countries, no measures at all. As all the countries criminalise the purchase of sexual acts from children below the age of 18, the article examines whether this has afforded trafficked children effective protection against sexual exploitation. One key element in the crime of purchasing sex from a minor is knowledge of the child's age. The subjective elements that states require range from strict liability (below certain ages) to negligence, and their practice also varies. The article ends by discussing the lacunae that remain before states can be said to secure trafficked persons' right to effective protection against sexual exploitation.