"The relationship is one of obvious asymmetry of interdependence... The EU has all the benefits to offer (principally accession, trade and aid), and far from all of her component member-states are sure they want all the CEE applicants to join. The CEE countries, by contrast, have little to offer the EU, given their tiny economic size, and little to bargain with because the desire of their political elites to join is generally much greater than that of the member-states to let them in. This asymmetry of interdependence allows the EU to set the rules of the game in the accession conditionality" said Heather Grabbe. Any candidate country wishing to join the EU must meet the political, economic and democratic criteria and has to fully transpose and implement EU laws and standards. The candidate Central and Eastern Europe Countries (CEECs) have been taking on all the obligations of EU membership for some ten years now, at the requirement of the EU to transform their domestic policies and institutions. On 1 January 2007, Bulgaria and Romania successfully made accession to the EU and finished the largest fifth round enlargement. This thesis focuses on Bulgaria whose political, economic and democratic conditions are catastrophic after decades of former Soviet's Communist rule. It probes into the impact of EU accession conditions on domestic institutional adjustment especially in the area of fight against corruption. The Copenhagen European Council (1993) set the criteria for enlargement towards the Central Eastern European countries, by including anti-corruption in the democratic conditionality. Corruption in government and public administration is a complex and pervasive phenomenon in Bulgaria. Anti-corruption is constantly the area of serious concern for Bulgaria in the Eu monitoring report. It involves a wide range of matters in domestic institutions such as the government, the parties and judiciary, etc. being a very important topic of the political domestic establishment and of the society in general. Linking the Europeanization concept with the new institutionalism theory as an analytical tool, the thesis carries out a justifiable study of the Europeanized adjustment of the anti-corruption measure and the transformation of its relating institutions in Bulgaria. The thesis tries to depict, by describing and analyzing the impact of the Europeanization process on the policy choices of member and candidate states. The author holds the opinion that on the one hand, the EU enlargement is regarded by the EU as a chance to deepen its institutional integration; on the other hand, it is also a historical chance for the acceding countries to re-mould their domestic institutions and to realize full-scale Europeanization. Key words: anti-corruption, new institutionalism. Europeanization, EU enlargement