More and more research confirms the influence of monetary policy over supply through the costs level (especially in reference to the working capital costs) and over the marginal costs of a given enterprise which influences their pricing policy and manufacturing decisions. Thus, it has become a necessity in the monetary policy’s effectiveness to take into account cost channels of transmitting monetary policy into economy, along with identification of factors determining its effectiveness. It may point out to the stronger reaction of the central bank in order to repress costly inflationary pressure; it may as well point out to a lower interest increase in order to not increase inflation expectations. It depends on the specificity of a given economy – to be precise, the role of a cost channel and market expectations, as well as the strength of an interest rate channel. The central bank should analyze the effects of its actions in order to neutralize negative consequences and increase its effectiveness. Thus, when it comes to the cost channel, it comes as more effective for the central bank to focus on the inflation goal and to base the monetary policy on the aim of achieving this goal. To strengthen the effectiveness and credibility, it is necessary to create a realistic strategy should economical crisis occur.