This degree project will explore the Wizar-of-Oz approach to perform empirical studies. The scope of the project includes areas of application, strengths, weaknesses and ethical considerations. The psychological aspect will also be covered and many examples of past experiments will be discussed. In spite of the ethical arguments and limitations agains the methodology, the conclusion is that it is a good technique that should be considered as a choice of methodology as long as the requirements of the methodology are met, the experiment must for example involve a task that a human is able to simulate in a reasonable manner.