This chapter is concerned with the impact of the EU enlargement on the Commonwealth of Independent States (CIS) countries, particularly in terms of GDP growth, trade, and the impact on the overall economic system. It discusses profound long-term changes, the time perspective should be at least a decade. The chapter utilizes unweighted averages, as the purpose is to illustrate the relative position of various countries. It shows empirical tests of the determinants of exports of former socialist countries. The chapter suggests that the statistical problems are considerable. The effect of accession of an adjacent group of states on growth of the CIS states is of course not immediate. The major economic reality in the CIS states is that the industries inherited from communist planning are outdated and sometimes perverse vis-a-vis the economic endowments of the countries. The post-communist countries vary considerably in terms of the rates at which they have eliminated barriers to structural change.