Although a depressive state is known to occur following the resolution of an acute psychotic episode, little research has investigated its etiology, course, prognosis and treatment. Very often the depression is mistaken for an extrapyramidal-like syndrome--the secondary effect of antipsychotic medication--as a sense of inevitability assails both the patient and therapist. Post-psychotic depression, far from being an obscure and undefined clinical picture, has the characteristics of a clear-cut syndrome. Nevertheless, it was only recently referred to as a distinct entity in psychiatric classification systems. As a result, different researchers used varying criteria for the definition of the phenomenon, and the data collected in the different studies are therefore difficult to compare. We present a critical review of the data published to date, with emphasis on the importance of early recognition and treatment of post-psychotic depression.