This thesis concerns the integration of the eight CEEC's (Central and Eastern European Countries) in the Monetary Union. Rather than to analyse the institutional criteria of convergence which are officially apply by the European Institutions, it carries out an economic and econometric analysis related on macroeconomic mechanisms of these economies. Chapter one studies the co-movements of real and monetary variables and also the convergence of the movements of these two categories of variables between the former members and the news members of the UE. Chapter 2 and 3 are related to the transmission channels of the monetary policy. We emphasize that the transmission mechanisms of monetary policy depend on the exchange rate regimes of these co...