This study presents a diagnosticframework and methodology to evaluate a pharmaceuticalsystem s vulnerability to corruption and to determine whichcorrupt practices can have a major impact on the system sultimate efficiency. We thus provide: (a) a systematic andquantifiable assessment of the extent to which a country spharmaceutical system is vulnerable to corrupt practices;and (b) the identification of potential actions to increasethe system s resistance to corruption, and ultimately,improve access of the population to good quality, essentialmedicines. The diagnostic framework and methodology permitusers to identify key decision points in the pharmaceuticalsupply and distribution system (registration, selection,procurement, distribution, service delivery and use); assessthe extent to which a country s current policies andpractices at each of these key decision points make thesystem vulnerable to corruption; and understand the range ofoptions that could reduce this vulnerability. Thisdiagnostic tool has been designed for use by World Bankhealth specialists involved in health lending operationsthat include pharmaceutical components, and their nationalcounterparts to help them identify points of vulnerabilityin the pharmaceutical system, address these points, and thushelp ensure that pharmaceutical expenditures are maximized.While developed in the context of the health systems ofLatin America and the Caribbean (and implemented in a pilotstudy in Costa Rica), the methodology can be modified withease so that it is applicable to other regions.