To deter hard core cartel activity, the sanctions imposed on cartelists must produce sufficient disutility to outweigh what the cartelists expect to gain from cartel participation. Traditionally, monetary sanctions against undertakings have been the primary countermeasure against cartel violations. However, considering the limitations of financial penalties, increasing attention has been given to the use of non-monetary measures against corporations as well as individuals. This article contends that custodial sentences are the ideal sanction for countering cartels. The article argues that the threat of imprisonment is the most effective tool in combating anti-competitive practices. It is furthermore acknowledged that certain conditions must be fulfilled within an anti-cartel law enforcement regime in order for the sanction of incarceration to work effectively.