Based on historical and current contributions, the operational diagnostic approach is examined from a psychopathological point of view. Operational diagnostic systems in psychiatry are characterised by an atomising approach. In this context, psychopathological symptoms are interpreted as elementary entities which can be combined into a specific diagnostic category. Many years before operational diagnostic systems were introduced into psychiatry, however, such an atomising procedure was criticised by authors like Karl Jaspers, Willy Mayer-Gross or Klaus Conrad. Furthermore, validation of diagnostic criteria of operational diagnostic systems has not succeeded so far using biological findings or results of family and follow-up studies. This may be one reason for the fact that categorical approaches in psychiatric diagnosis are questioned increasingly and dimensional diagnostic models are suggested.