Monetary crises which occurred in the last decade have afflicted mostly countries whose macroeconomic policies were based on fixed or strongly stabilised exchange rates. This experience have brought about discussions whether the choice of the exchange rate regime may make a currency more or less vulnerable to crises, and also indirectly influence the stability of a country's entire economic system; whether free float exchange rates regime may protect the economy from foreign currency crises, whether such a crisis is possible at all in the context of free float exchange rates.

In order to answer the questions, the article reviews the models of monetary crises in the context of the evolution of the exchange rates policies in the world in the recent years and international experience concerning the occurrence of monetary crises in different exchange rate regimes.

Two radically different models of exchange rate regimes are compared in order to reveal the characteristics which make the fixed exchange rate regime more vulnerable to and the free float exchange rate regime more resistant to monetary crisis.

The article outlines the trends observed in applying different exchange rate policies. In the recent years, a clear polarisation of exchange rate regimes has been recorded: the number of countries where radical versions of exchange rate mechanisms are applied increases, while the number of those where mixed mechanisms are used decreases. Abandoning of mixed systems in favour of extreme systems - either fully fixed or fully free float mechanisms - is in fact a quality change in monetary policies. The countries which choose the currency board regime make their monetary policies strictly dependent on the policies applied by the country whose currency is chosen as an anchor, whereas the countries which introduce free float exchange rate regime gain autonomy in monetary policies. The polarisation of exchange rate regimes, and what follows the principles of monetary policies, leads to adopting policy rules which are more transparent and more credible.

The article undertakes to analyse Polish exchange rate policies from the point of view of vulnerability to crises and presents the experience gathered in the periods of considerable depreciation of Polish zloty exchange rates in foreign currency markets. Also the evolution of Poland's exchange rate policies is discussed. This historical presentation proves that Poland is one of the countries which have successfully passed from a fixed exchange rate system to mixed mechanisms and finally to a fully free float exchange rate system. This was possible thanks to the application at the right point of appropriate exit strategies and avoiding monetary crisis as defined by generally applied definitions quoted in the article.