The concept of psychogenic psychosis has always been regarded with scepticism, since it seems to harbour a contradiction in itself: Psychogenic mental disturbances are amenable to a rational approach, that is to say, they are understandable, whereas psychoses are incomprehensible mental disease patterns in respect of their content and course. Nevertheless, psychogenic psychoses have been described fairly often ever since scientific psychiatry came into being; in fact, they are being diagnosed quite frequently in some countries. For the purpose of helping to clarify these theoretical and practical difficulties, the article explains the history of the concept, the clinical patterns of manifestation, and the course of psychogenic psychoses, as well as the concept of their origin. An attempt is made to reconcile the immanent contradictions, and to demonstrate that this is actually a fruitful extension of the scope of the theoretical fundamentals of psychiatry.