In the nineties Polish commercial banks have faced considerable changes in their internal organization, and, as a result, they have abandoned previous organizational structures and introduced forms worked out by the banking theory and practice in different countries. The article attempts to classify existing solutions presenting basic models of banks' organizational structures, being models for continuous changes. Conclusions included in the article are the result of the survey on formal organizational structures of about thirty commercial banks in Poland in the period stated above. On this base a traditional functional structure, i.e. federal structure, and the banking matrix structure, both used nowadays, have been discussed. The concept present allows for integration of several attempts of the related literature to compare internal organization of banks with the theory of organization and Polish banks' experience. In practice, structures fully in compliance with the models presented can be rarely met which is due to the relative novelty of organizational changes and overlapping of solutions characteristic for various types of bank structures, associated with different needs and conditions of banks' functioning. Therefore, in order to facilitate the comparison of the models described, basic features and prerequisites of various organizational structures have been presented.