This study is a content analysis of wiretapped conversations and police interviews concerning the criminal case of ‘Operation Koolvis’: an investigation into a Nigerian human trafficking ring for sexual exploitation in Western Europe. The criminal network traffics women from Nigeria, via the Netherlands as a transit country, to become street prostitutes in Italy. The aim is to explore the role of ‘voodoo’ in the functioning of the organization, applying transaction cost economics and rational choice theory. Four main categories of voodoo use were found. Firstly, voodoo is a coercive mechanism. Secondly, it is used cynically in cooperation between traffickers. Thirdly, there is non-cynical mention of voodoo as a belief system. A fourth category concerns voodoo priests as independent enforcers of contracts.