Aiming to contain vast and fast rising expenditure levels, estimated to amount to 8.2% of GDP across OECD countries in 2003, national healthcare reforms cannot avoid rationing, that is withholding beneficial interventions from needy individuals. Yet, a substantial part of a nation's healthcare spending is typically diverted in illicit ways – rendering otherwise feasible care unattainable and undermining the legitimacy of private and public services. In the US, healthcare fraud and abuse reportedly accounts for around 10% of total outlay, i.e. $120bn per year. In the UK, prescription crime in 2003 was estimated to amount to £115 m. In Lower Saxony, one of Germany's 16 Länder, insurance fraud alone accounted for €40 m in 2003. But cases are not always clear cut and are not always easily dealt with. There is often substantial ambiguity in defining actually improper conduct, identifying such behaviour among vast numbers of cases that are handled annually, telling errors apart from criminal intent, and choosing adequate regulatory responses.

Four classes of corruption in healthcare are typically distinguished: bribes may be paid to get access to better service (demand-side) or service contracts (supply-side). Some of these, such as kickbacks and fee-splitting for referrals, may be induced by receivers who are deliberately not delivering services or decisions; others may be given to enable otherwise impossible service provision; others again may involve a gratitude payment to ensure better treatment in the future.