Since the early 20th century, a group of non-affective psychoses with acute onset and brief duration have been described in different countries and under various names, including cycloid psychosis, bouffée délirante, and reactive psychosis. These psychoses share a number of characteristics, including benign course, greater prevalence in women than men and in developing countries than industrialized countries, and high prevalence of premorbid psychological and physiological stressors. However, the variations in names and minute details of symptomatology have overshadowed the basic similarities across these various descriptions. Confusion in classification persists in the two contemporary diagnostic systems, the DSM-IV and the ICD-10. We believe that most cases of these psychoses could be captured under a broad, unified category of non-affective psychosis with acute onset and brief duration, and urge the authors of the upcoming revisions of the DSM and ICD to create such a category. A unified diagnostic category for these disorders would reduce unnecessary fragmentation in the diagnostic systems and assist in the progress of research on these rare conditions.