The proof of a drug's efficacy in randomized controlled trials is fundamental to therapeutic concepts determined by evidence-based medicine. Clinical trials according to the German Medicinal Products Act are performed by the pharmaceutical industry as company-sponsored trials (CST) driven by commercial interests or by non-commercial facilities as investigator-initiated trials (IIT), typically implemented by University Hospitals. In areas with no commercial interest, IITs are the driving force that generate scientific progress leading to treatment optimization. Therefore, non-commercial or investigator-initiated clinical trials are indispensable for improving medical care. To ensure the safety of trial participants and the quality of the data obtained, clinical trials are controlled by many legal regulations and internationally accepted quality standards. Therefore implementation of a clinical trial requires profound knowledge, qualified personnel, appropriate infrastructure, and substantial financial resources. In IITs unlike CSTs this has to be accomplished by the University without the assistance of the pharmaceutical industry. Since teaching of skills needed to perform clinical trials is still largely neglected in medical school and during residency this review addresses the (in clinical trials) inexperienced physician and outlines the characterization of a clinical trial, the range and division of responsibilities and the performance of clinical trials according to the German Medicinal Products Act.