:  This study examined the effects of monetary policy on aggregate bank lending of deposit money banks in Nigeria from the period of 1984 to 2020. It specifically established the effects of monetary policy on aggregate bank lending of Nigerian deposit money banks and analysed how monetary policy affects aggregate bank lending activities of Nigerian deposit money banks. The study made use of secondary data obtained from Central Bank of Nigeria and National Bureau of Statistics to carry out econometrics and regression analysis on certain macroeconomics variables that were combined and estimated. The findings revealed that monetary policy rate, money supply and exchange rate have significant and positive effects on aggregate lending to private and public sectors by deposit money banks in Nigeria aside inflation that has a negative and insignificant effect. The effect of these is that monetary policy is the true parameter of measuring the effects of aggregate bank lending of deposit money banks in Nigeria. The researcher therefore concludes that monetary authorities need to supervise thoroughly the deposit money banks activities to enable them comply with all regulatory frameworks issued by the CBN. Also the objectives of monetary policy should be spelt out without ambiguity because of its multi-target characteristics so that conflict of objectives and instruments are avoided and resolved