The 1992 Nobel Prize winner, Gary Becker, has been the first economist to apply in the 1960s the principles and methodology of microeconomics to individual criminal behaviour. After shortly discussing on Beckerian approach, Chapter one focuses on optimal anticrime policy, namely those instruments that have a deterrent effect against crime and are, in the meantime, able to minimise the cost of crimes for the society. Thereafter, the thesis concentrates on some other contributions following the seminal work of Becker. These contributions move their attention from the factors affecting the individual decision to commit a crime to the interactions with the social and environmental groups to which they belong. This allows to bring to the fore some shortcomings of Becker's theory and the reasons why it appears unable to explain the existence and to adequately fight organised crime, and mafia in particular. Chapter two show that the "Blood pact" (Patto di sangue) among affiliates represents the key element able to stabilise over time criminal organisations like mafia. Such stability is necessary for mafia to attain a more effective control of the territory. Game theory, and specifically the prisoner's dilemma, provides a sound theoretical explanation of the reasons why the bloody deal makes it profitable for the individual affiliate to mafia to belong to the organisation, rather than acting individually. Moreover, it suggests that traditional anticrime policy is, by and large, ineffective to contrast mafia and that, conversely, pentiti (justice collaborators) can be an important instrument, as the judges Giovanni Falcone and Paolo Borsellino claimed, and as all the judges who are now on the front line in the fight against mafia, such as Gian Carlo Caselli and Pietro Grasso, continue to claim. Chapter three attempts to answer the question: "Why should a Mafia affiliate surrend to and collaborate with justice?" Game theory can be again used to analyse the factors that affect the benefits and costs of justice collaboration and the analysis concentrates in particular on Art. 41bis of the Italian Penitentiary Law. It tries to show that game theory provides an enlightening theoretical context to study the potential impact of recent reform of the institute of justice collaboration recently implemented. Finally, the thesis provides a comparative analysis of the Italian and US law on the institue of pentiti on which the judges Falcone and Borsellino often referred to in their writings and discourses.