A major part of clinical research in Denmark involves clinical testing of pharmaceuticals sponsored by the pharmaceutical industry. All these trials are carried out according to Good Clinical Practice (GCP) and necessitate a close working relationship between responsible investigators and the pharmaceutical industry. It is of mutual interest that these trials should have a high scientific standard and that the integrity of patients always has the highest priority. Many guidelines, laws and conventions regulate this area to ensure the fulfilment of these goals. In the present article, we describe the roles and responsibilities that pharmaceutical companies have to comply with.