Clinical trials are an essential part of the development and licensing of medicinal products. They are intended to prove the efficacy of new medicinal products and to demonstrate their safety. Clinical trials are performed before the product concerned is placed on the market. Since 2004, they have to be approved in Germany by the respective competent federal higher authority (depending on the type of product, either the BfArM or the PEI). This approval is required in addition to the favourable opinion from the competent Ethics Committee. However, after the medicinal product has been granted a marketing authorisation, clinical trials also provide important findings on long-term effects of treatments or data on off-label use.