In the middle-May 1995 NBP introduced a new mechanism of fixing major exchange rates in Poland's foreign trade, i.e. US dollar and German mark. Similarity of the new exchange rate regime and the market speculation consist in that the central rate related to the US dollar and German mark presented by NBP to commercial banks at the beginning of each business day is not legally binding and its breach is not prohibited. The second market participants, i.e. commercial banks, present their own preferences as to foreign exchange deals. Although NBP, introducing the new regime, ceased an administrative fixing of the US dollar and German mark rates it has some - however, only indirect - influence on the market play developments, and therefore on exchange rates, being the result of the play. And namely, it can actively affect the relations between supply and demand through additional purchases of foreign currencies or through increasing their supply.