Estimates suggest that international reserves of the Eurosystem could be reduced by one third to half ($130-$170 bill.) of its existing level after the introduction of the Euro. While the ultimate decision, whether and how to use these excessive reserves (public debt repayment, financing of a fund, financing of a tax cut) is a political one, some general results can be stated: First, since reserves earn interest revenue, a large part of which is transferred to the government anyway, moderate (but still positive) economic gains can be expected from a reserve reduction. Second, reserve reductions exceeding a certain threshold require the ECB's approval, which could, however, only be rejected if the envisaged measures were inconsistent with the ECB's monetary and exchange rate policy. Given that unintended macroeconomic effects can easily be avoided by a carefully planned and coordinated reserve reduction, such a rejection by the ECB - which is subject to the review by the European Court of Justice - is only hard to justify. Equally important from a legal point of view is that reserve reductions, effected as transfer of an extraordinary gain to the government, do not constitute monetary financing as prohibited under Art. 101 EC Treaty. Finally, reducing reserves to an adequate level would also eliminate incompatibilities and conflicts of interest between monetary and investment policy by the central banks and reduce their field of operation to their core task: the conduct of monetary policy. Thus, a carefully planned and coordinated reserve reduction can be supported from both an economic as well as legal point of view. / Series: EI Working Papers / Europainstitut