This paper is an empirical investigation of the international transmission of US monetary policy in South Korea. It combines modern mainstream macroeconomics in monetary transmission with various adjusted versions of the IS-LM model to estimate the relationship between US monetary policy and the Korean economy. The Ordinary Least Squares analysis confirms the statistical significance of US money supply, with other relevant factors, in determining Korea?s output, exports, interest rate and money supply. The results are robust to an alternative measure of US money supply while they vary slightly with the introduction of a time factor to possibly account for capital controls. This study adds to the current literature by extending the study period to cover over forty years of trade history between the US and Korea.