This thesis examines three different aspects of monetary policy in a varying sample of developing countries, with some Islamic banks. The first essay estimates a variety of interest rate rules for the conduct of monetary policy for Indonesia, Israel, South Korea, Thailand and Turkey, in both high and low inflation conditions. The findings are that the reaction of monetary policy to both inflation and output gaps differs between the high and low inflation regimes and that the exchange rate channel is important only in the low inflation regime. The second essay examines the bank lending channel of monetary transmission in Malaysia, a country with a dual banking system, with both Islamic and conventional banks. The results show that Islamic credit is less responsive to interest rates shocks than is conventional credit, in both high and low growth conditions. In contrast, the relative importance of Islamic credit shocks in driving output and inflation is greater under low -inflation conditions and higher Islamic credit leads to higher growth and lower inflation in such conditions. The third essay re-examines the question of causality between credit and GDP between two sets of countries one set without Islamic banks and the other set with dual banking systems, including some Islamic banks. The results suggest long-run causality from credit growth to GDP in countries with only Islamic banks.