This study examines the effect of anticipated and unanticipated monetary policy shocks on the effectiveness of monetary policy transmission mechanism in Nigeria by estimating a sticky-price dynamic stochastic general equilibrium (DSGE) model using Bayesian estimation approach. Four major transmission channels (exchange rate, interest rate, credit and expectation) are considered due to the economic and financial conditions of Nigeria. The study employs quarterly data from 1986:1 to 2013:4 and data are sourced from World Development Indicator (online version). Results show that unanticipated monetary policy shock has short-run impact on monetary policy transmission channels, while anticipated monetary policy shock has long-run impact on the monetary policy transmission channels. The study, therefore, concluded that efforts should be directed at reducing the unanticipated monetary policy by announcing government policy at the beginning of the year so as to reduce people’s expectation.