Clinical research trials (both academic and industry sponsored) are increasingly playing a role in various medical disciplines, including younger fields of clinical trial interest, such as nuclear medicine research. Knowledge for and compliance with good clinical practice (GCP) is essential for anyone involved. In this review article, key aspects of GCP and the responsibilities of investigators, monitors and sponsors are described. In addition, a comprehensive overview of the historical background on the development of GCP from the US Pure Food and Drugs Act of 1906 over the Nuremberg Code, the Kefauver–Harris Amendments and the Declaration of Helsinki until now is given. Knowledge of the historical background may help understand the developments in GCP.