[Principles of controlled trials (author's transl)].

Wrong interpretations of the results of experimental trials on animals and of clinical studies block up scientific progress in medicine and withhold the best possible treatment from the patient. They are caused by concomitant influences independent of or dependent on treatment. Such bias is avoided only by designing "controlled trials". Their definition and principles are discussed here. In clinical drug research these principles can almost always be brought into concordance with the demands of medical ethics.