Inclusion criteria

Primary research studies: with data on the health status and/or access to health care of undocumented migrants in one or more of the EU27 countries; in a language in which authors were proficient (i.e. Dutch, English, French, German, Italian, Portuguese, Spanish); published from 1 January 1990 to 31 December 2012.

Exclusion criteria

Studies were excluded if: no primary data was collected (e.g. many used hospital-based records or audits from other health institutions); data was not disaggregated by immigration status (e.g. some studies targeted migrants in general); documents duplicated higher-quality study results already included (e.g. meeting abstracts were excluded if original peer-reviewed articles were available); they were not research articles (e.g. small ad hoc surveys, comments, notes, personal views, discussion papers, books); they were published in a language other then those in inclusion criteria and no English abstract was available; data was collected before a respective state was a member of the EU; and the country was an overseas territory of an EU member state.