An enlargement of the eu to Central and Eastern European Countries (CEECS), would constitute an unprecedented change : ceecs transitions are underway, and eu is currently facing major transformations, reforms, uncertainties and challenges. This paper intend to evaluate macroeconomic consequences of an enlargement, with the International Macroeconomic Model Mimosa. Our study shows that an eastern enlargement would have beneficial macroeconomic consequences relatively modest for the EU current members, but quite substantial for the newcomers. It appears that trade openness and financing are essential for the success of an enlargement process. An increase in Structural Funds currently allowed to the CEECS -relatively modest for the current eu members- would greatly foster more rapid and sustained growth in these countries, and in the rest of Europe, so that the additional transfers would soon be self-financing. This study shows that obstacles to enlargement process do not come from economic difficulties, but mainly stems from political and strategical issues.
