In this brief, we analyze, empirically, the effects of quantitative easing on interest rates and the economy in the USA, Japan, the UK, and Europe. Using an event-study methodology, we find that the measures undertaken by the Federal Reserve and Bank of England, which focus primarily on bond purchases, are much more effective in lowering interest rates than those undertaken by the Bank of Japan and the European Central Bank, which have relied more heavily on lending to private financial institutions. Over the QE-related events, government bond yields in the USA and the UK decline cumulatively by over 100 basis points at medium and longer maturities, and more than 50 basis points at shorter maturities. In contrast, an average fall by only about 20 basis points is found for government bond yields in Japan, while mixed results are found for those in the euro area. The different impacts of QE on interest rates across economies, however, should be understood in light of their respective financial system structures.