The paper analyses monetary policy transmission mechanism in Nigeria. Vector auto-regression model is estimated for the pre-reform and post-reform periods. Variance decompositions and impulse response functions are examined to see whether there are any changes observed in the monetary transmission mechanism after the reforms. Different systems are estimated in each period using alternate variables as measures of monetary policy shocks. When compared results from the two estimation periods, we noted that both the responsiveness of prices and output to policy shocks and the magnitude of their forecast error variance decompositions, explained by these variables, have increased since the reforms. There is evidence of the bank-lending channel both before and after the reforms. Of the mechanisms estimated, the exchange rate and lending mechanisms seem to be the most important mechanisms for transmission of policy shocks to both prices and output during the post-reform period.