Regardless of new technologies or products what banks will offer for its existent and future customers, the banks will not be able to hold them, if a special attention will not be turned to one of the main undisclosed value of balance sheet - customer capital. The goal of this study is to define the concept of "customer capital" and its role and impact on the bank's financial performance. To achieve the results were used the following research methods: a questionnaire, quantitative and qualitative methods, including the method of sociologic research, monographic and descriptive method. Methodology – with a sociologic research method in the research was clarified facts: what are the customer capital and what are its determinants. Based on the theoretically obtained data hypotheses were established, which were tested in several banks using a questionnaire. The obtained results confirm that in the surveyed banks are used different methods of customer capital accounting and the methods effect on banks' financial performance.