To estimate how monetary policy works in small open economies, we build a dynamic stochastic general equilibrium model that incorporates the basic features of these economies. We conclude that the monetary policy in a group of small open economies (including Australia, Chile, Colombia, Peru, and New Zealand) is rather similar to that observed in closed economies. Our results also indicate, however, that there are strong differences due to the shocks from the international financial markets (mainly risk premium shocks). These differences explain most of the variability of the real exchange rate, which has important reallocation effects in the short run. Our results are consistent with an old idea from the Mundell-Fleming model: namely, a real depreciation to confront a risk premium shock is expansive or procyclical, in contradiction to the predictions of the balance sheet effect, the J curve effect, and the introduction of working capital into RBC models. In line with this last result, we have strong evidence that only in one of the five countries analyzed in this study does not intervene the real exchange rate, the case of New Zealand.