This Master Thesis examines the effects of Quantitative Easing (QE) in Japan, the United States and the Euro Zone. As Quantitative Easing is an instrument used by central banks, the thesis begins in explaining the system of central banks and their monetary policy. Furthermore the connection between economic indicators and monetary policy is demonstrated. Major effects of QE are also being identified. Within the main part of the thesis, the programs of the BoJ, the Fed and the ECB are explained and critically analyzed. The author shows, if QE-Programs bring along positive effects within the mentioned economic areas and if so, which measures have been identified to be highly effective. Comparing relevant studies within this field supports to evaluate each program. These studies are confirmed by efficiency on the one hand, and congruence on the other hand. According to history, first Japan (first program in 2001), then the United States (first program in 2008) and finally the Euro Zone are examined. Specific effects like the information channel demonstrate a positive influence on economic growth and inflation rates. The analyzed studies nevertheless cannot prove that QE is sustainably supporting the real economy. This is also shown by the used economic data of the last years within this thesis. Therefore for example, Japan is not able to free itself from the deflation spiral, and the heterogeneous Euro Zone can demonstrate a stabilizing effect only within some few states. In some investigated economic regions a short-term tendency for relaxation can be identified, but i cannot be clearly linked to Quantitative Easing.