Development and diversity is connected not only with GDP or GNI per capita level, but often with measurement of another socioeconomic indicators as rate of unemployment, health and education fields or households equipment. The aim of this paper is, with the quantification of socioeconomic indicators, to describe the development of regional diversification using cluster analysis at the regional level of selected Central European Countries after enlargement of European Union. The regions at NUTS 2 level of the Czech Republic, Hungary, Poland, Slovakia and Slovenia were selected for this purpose. There are 37 regions on the NUTS 2 level, eight in the Czech Republic,seven in Hungary, sixteen in Poland, four in Slovakia and two in Slovenia. The research was made in the first two programming periods after the big enlargement of EU from 2004 to 2006 and 2007 to 2013 with their comparison. According to hierarchical cluster procedures, using the Ward method, the five clusters were set and it was found that regional diversity still exists and positive development recorded only forty nine percent of the monitored regions.