Agata Gemzik-Salwach
pages: 57-65, JEL classification: G10, G21, C33, Key words: interest margins, banks, bank products,   Abstract: The article concerns the possibilities to assess the effectiveness of bank services basing on an analysis of their interest margins, and its aim is to show the informational capacity of those measures. The first part of the article discusses theoretical issues related to setting various types of interest margins and on their basis specifying interest margin discrepancies. Then results of empirical research are presented which were conducted basing on the data from quarterly financial reports of selected WSE listed banks in 1998-2009. The analysis covered the shaping of all the discussed values in time, both for the bank sector as a whole and in relation to particular banks.