Abstract. This paper presents the main costs and benefits of accession to the EMU countries, different transmission mechanisms of monetary policy measures villages as national fiscal policies and the procedures for quantifying the effects of these measures on the real economy. Are costs caused by the occurrence of asymmetric shocks, different preferences of countries of inflation and unemployment and due to institutional differences in the labor market or something to with different rates of growth. The resulting benefits are presented after elimination of transaction costs and decrease welfare gains due to uncertainty after joining the EMU.

Keywords: optimum currency area; cost; benefits; European Monetary Union; euro; convergence.