Monetary policy can significantly affect real economic activity, at least in the short run, but the size and the duration of short run effects are intensely debated. Using a structural VAR (SVAR) approach, the purpose of this paper is to investigate monetary transmission mechanism in Iran during 1989:2–2007:3.The results indicate that in the long run, there was not any monetary transmission throughout channels in both models, but in SVAR credit channel had an effective role. Also we found that credit channel is the most effective channel in monetary transmission mechanism in Iran. These findings suggested we must monitor credit channel to be able to control monetary policy properly.