Monetary transmission mechanism includes some channels in which monetary policy influences on macroeconomic variables such as the output and inflation. In this study, the effect of monetary policy tools including interest rate, exchange rate and money supply on the variables of monetary policy targets including inflation and output is examined through VECM methodology over the period 1989:2-2007:2. Our findings show that in long-term, monetary supply is the most important variable influencing the price followed by the variables of output and exchange rate, respectively. Exogenous-being of interest rate indicates that this channel is underdeveloped and there is no monetary policy rule like Taylor rule in Iran & apos; s economy.