The formation of the European Union (EU) is the one of the biggest political – economic events of the last 50 years. EU development and optimization process is still incomplete, with still evolving EU economic foundations and financial system. The aim of this study is to explore the effects for EU member states that were created by the EU enlargement processes. The paper focuses on such indicators as GDP, employment, public debt, and reflects its dynamics in periods of the years 1995, 2004 and 2010. The study uses traditional mathematical, statistical and economic analysis methods, such as data grouping, comparison, average level and trends detection, as well as visual analysis (graphical) method. Study result – author divides EU countries into several groups, based on their economic specifics; (it is possible to use similar development politics for these groups).