One can hardly find a country without monetary policy. As a matter of fact, monetary policy has gained a solid ground in the Nigerian economy. However, in light of various economic problems in Nigeria, it would seem the benefits of monetary policy are yet to be fully harnessed. The purposed of this study is to analyse the impact of monetary policy with Nigeria being the case study. With regards to the data analysis, regression analysis was applied. The study covers the effectiveness of monetary policy. The study revealed that the level of effectiveness of monetary policy is highly influenced by the Central Bank of Nigeria (CBN).