Psychoneuroimmunology was for the first time comprehensively described about 20 years ago. The influence of mental status on the course and outcome of a number of diseases, however, was suspected a long time before. Also the links between mental affective disorders and the immune status were repeatedly suggested. The authors in this paper shortly reviewed the most important clinical as well as experimental evidence which at present strongly supports the concept of a close and bidirectional communication between central nervous, neuroendocrine and immune systems. The most important anatomical, physiological as well as pharmacological experimental data, which were obtained by the authors during 20 years of research in this field, are presented. The data strongly suggest that in the very next future we will not only better understand a very complex communication between mind and body, but also completely new types of compounds might become available.