A 50-year-old woman is admitted to the emergency ward by reason of her psychotic state. Because she has a history of psychiatric problems and has been previously diagnosed as having borderline personality disorder it is assumed that she has had a brief psychogenic psychosis. When the psychosis recurs and the symptoms increase in intensity the patient is given a computerized tomography brain scan. The scan reveals a subarachnoid haemorrhage. In discussing this case history we try to interpret the symptoms of this neurological disorder against the background of the premorbid psychiatric diagnosis. We supplement our interpretation with data from case histories reported in the literature.