The discovery of chlorpromazine for the specific treatment of schizophrenic symp toms and, later on, of imipramine for the specific treatment of depressive symptoms marked a new milestone in clinical psychiatry and basic neuroscience 40 years ago. The exploration of biochemical mechanisms of action of these psychotropic drugs created new theories on the pathophysiology of psychiatric disorders, such as the dopamine hypothesis of schizophrenia and the catecholamine and serotonin hypotheses of depression. Thus the discovery of these biological treatments had a major impact on natural science-oriented research. Biological psychiatry as we know it today has its origin in these psychopharmacological drugs and influences many disciplines in psychiatry. It was a fortunate coincidence that Hans Hippius, whose 70th birthday we celebrated this year with an international symposium, started his professional career during this time in the 1950S. He was one of the early pioneers in clinical psycho pharmacological research and enthusiastic about both the scientific and the thera peutic prospects of the new psychotropic drugs. He has worked in this field for more than three decades and has made many lasting contributions to biological psychiatry. Among the many activities, his contributions in the development of the new atypical antipsychotic drug clozapine should be mentioned.