The paper seeks to determine the structure of selected banking services markets through the concentration ratio method, as well as capture the concentration trends in the 90s against the background of foreign banking systems.

The degrees of concentration computed as the classic concentration ratio (CR) and the Herfindahl-Hirschman (the HH) Index of average market concentration indicate that competition in the 90s became more intensive. The analysis covers the markets for key banking services offered by Polish banks, such as deposits from the non-financial or government sectors as well as loans extended to them.

In comparison with the EU figures, concentration degree computations for the Polish banking sector reveal scope for further concentration. If that happened, the market position of the biggest banks would be strengthened. Among other considerations, the author wishes to point out that the increasing concentration in the financial services market may influence the stability and efficiency of the financial system.