Abstract EU enlargement and the incorporation of the acquis communautaire are widely seen as successful and emboldening the integrity of political, administrative and legal institutions in Central and Eastern Europe (CEE). The analysis reported here describes the specific problems associated with affirming institutional integrity in the field of public procurement, which constitutes a 'tough test'. Public procurement is namely an area where the acquis swiftly gained pre-eminence in accession states, but whose complex regulations depend on a well-functioning judiciary, effective administrative supervision and limited corruption. The experience in Poland and Bulgaria, countries that represent different stages of institution building in this area, is compared. The results suggest that an EU-compatible public procurement regime is being consolidated throughout the CEE region. At the same time, that regime may only work well when boundaries between institutional subjects, as well as between the spheres of law, politics and economics, are upheld in post-communist countries.