Medical research refers to activities that are carried out in a methodically guided manner and are aimed at gaining knowledge in the field of medical science. An important subgroup of medical research is formed by so-called clinical studies for testing drugs, vaccines and medical products. However, the testing of new surgical techniques also falls under the term ‘medical research’, although in many cases - including in Germany - there is no specialised legal regulation for this type of research.

In the field of drug trials, a distinction is usually made between four methodological phases: In phase I trials, a new substance is administered to a small number of healthy volunteers for the first time and its tolerability is analysed. In phase II trials, a new substance is tested for the first time on a relatively small number of sick test subjects undergoing treatment to determine its efficacy and any side effects. In phase III trials, the efficacy and safety of a new substance is tested on a large number of test subjects. Phase IV trials are conducted after a new drug has been authorised in order to detect rare side effects and unknown interactions with other drugs.