Following a historical overview the current state of development of psychiatric diagnostics is reported. Instead of intuitive clinical diagnoses an operational classification is aimed at. In the next few years WHO will introduce a new revision of the International Classification of Diseases. Development and structure of the psychiatric chapter V (F) of ICD-10 are described. Different versions of this chapter will appear for use in clinical psychiatry, scientific research and general medicine as well as for the use of the general practitioner. In characterizing the different subchapters some criticism is expressed, which has arisen in the Commission for Diagnoses of the German Society of Psychiatry (DGPN). Finally current studies concerning the practicability, reliability and validity of ICD-10 chapter V (F) are described.