The aim of the present paper is the analysis of the functioning of the cost channel (working capital) in the mechanism of transmitting a monetary policy into the Polish economy as well as the attempt to assess its strengths. To accomplish the above-stated goal, one attempted to solve the following two research problems: is the cost channel operative in Poland patent and what is its strength and efficiency? What was also analysed is the correlation between the level of the benchmark rate of the National Bank of Poland [hereinafter also referred to as NBP] and the value of the working capital relative to current assets and to sales revenues made by the business enterprises in Poland in the period 2005-2017. By analogy, what was also subject to correlation analysis was the relation between the base interest rate of the National Bank and the value of investment expenditures in Poland. At the next stage, via an inductive method, one conducted a synthesis of the conclusions obtained by way of a comparative analysis of the results of one's own research against the backdrop of the ones obtained by way of the analysis of the influence of a monetary policy exerted on the supply side of an economy, with the latter results having been obtained in consequence of global econometric research. The correlation analysis thus conducted seems to corroborate the influence of the monetary policy pursued by the National Bank of Poland on real economic indices in Poland; and, strictly speaking, on financial