The present paper aims at achieving a comparative analysis of the structure of monetary aggregates, according to the definitions used by the European Central Bank and the National Bank of Romania, respectively. The relevance of such a comparison is justified by the changes adopted by the monetary authority from Romania at the beginning of 2007 in what regards the structure of aggregates M1, M2 and M3. The paper expresses opinions on the effectiveness and impact of monetary strategies implemented by the two monetary authorities, namely the two-pillar strategy used by the European Central Bank and the direct inflation targeting strategy implemented by the National Bank of Romania.