Czech Republic, Hungary and Poland will have to join the European and Monetary Union. Surprisingly, there is very little work on the welfare consequences of the loss of monetary policy flexibility for these countries. This paper fills this void by providing a framework to evaluate quantitatively the economic costs of joining the EMU. Using a two country dynamic general equilibrium model with sticky prices we investigate the economic implications of the loss of monetary policy flexibility associated with EMU for each country. The main contribution of our general equilibrium approach is that we can evaluate the effects of monetary policy in terms of welfare. Our findings suggest that these economies may experience sizable welfare losses as a result of joining the EMU. Results show that the cost associated with the loss of the monetary policy flexibility is bigger in the presence of persistence technological shocks, weak correlation of monetary shocks, strong risk aversion and a small trade share with the EMU