This paper examines whether in the analysis of the impact of monetary policy, the exchange rate can play a role along with the interest rate as a transmission mechanism of monetary policy effects on economic variables or not? For this purpose, the general dynamic stochastic equilibrium models were used in the form of a New Keynesian small open macro-economy; accordingly, in this study, the Bayesian approach has been implemented to obtain the estimates of parameters and conclusion in this model. To this end, Dynare was used, which is a general and suitable tool for Bayesian estimation in the context of dynamic stochastic general equilibrium models. This model was designed for the economy of Iran, considering oil-based economies and the currency substitution existence. Then, its calibration and simulation were conducted with Iran's economic data for the period 1995-2011. The results from model validation, univariate and multivariate recognition of Markov Monte Carlo chain and analysis of the model impulse responses show that in Iran's economy, the exchange rate plays a role along with the interest rate as a monetary transmission mechanism.