This chapter explores the financial penalties imposed for breaches of competition law in the EU and the UK. Broadly speaking, enforcers have three kinds of ‘weapons’ in their arsenal to use against those who attack competition: remedies, imprisonment, and fines. The first of these weapons may be the most powerful, and includes conduct, structural, and third-party remedies. Incarceration — the second weapon — is a well-publicized feature of the US system, and has been an option in the UK in relation to hard-core cartel conduct since the entry into force of the Enterprise Act 2002 (EA). The argument in favour of the efficacy of fines, the third weapon, is a persuasive one: companies take part in anti-competitive conduct in order to boost profits; remove those profits and the incentive for illegal conduct vanishes.