### Abstract

The search for QG effects has many aspects:

1. QG effects should violate the Einstein Equivalence Principle (EEP) or fundamentals of Quantum Theory. 2. QG effects are assumed to be very tiny. 3. Need for an appropriate experimental strategy. 4. Which effects are violations of EEP and other fundamental principles? 5. Which effects are QG effects?

Accordingly, a first approach for the search of QG effects is to search for violations of the EEP. We will describe in a systematic approach given by the structure of the EEP the huge variety of experiments which are needed to test the EEP and report on the present status of these experiments. When available predictions from quantum gravity inspired scenarios will be presented, too. We also describe experiments in te quantum domain. After the main experimental part we also make short remarks on the strategies of a search for qantum gravity effects, on the magnitude of the expected effects, and on criteria of what can be regarded as a quantum gravity effect. Finally we give some information about which experimental accuracies can be expected in the future.