EN
Monetary base is one of these economical categories which play the particular role not only in monetary policy but also in whole economy. The main aim of the article was to present changes and structure of monetary base in Poland, as well as to define causes of these changes. In analyzed period (2001-2007) volume of the monetary base systematically increased (+53,9 billion PLN). Financial reserve accrual's variations were caused by unequal level of debt of household and enterprises, foreign assets' influx into Poland, and most of all operations of the central bank.