Deposit and loan interest rates in commercial banks are determined by various factors that are both external and internal, as well as qualitative and quantitative. We explore in this article which of these factors and to what extent have set the deposit and interest loan rates and shaped the general change of direction for commercial bank behaviour during the period of economic transformation. In particular, there is an analysis of the influence of the overall economic situation and of the central bank interest rate policy on the level of rates in commercial banks. The analysis was carried out in the context of advancing commercialisation and privatisation of the banking sector and has been presented as a multi-aspect assessment. This analysis confirms that the real loan interest rate in market economy conditions favours or dissuades investment, and that such phenomena occur on a delayed basis.