The authors describe a new scale, the Post-Stroke Depression Rating Scale (PSDRS), specifically constructed to investigate the emotional, affective and vegetative disorders of stroke patients. They also report some preliminary data concerning the validity and reliability of the new scale and of its sections and the first results obtained administering the PSDRS to 68 stroke patients and 10 subjects affected by a "functional" form of major depression. The comparison between the results obtained on the PSDRS by patients classified (on the basis of DSM III diagnostic criteria) as having major depression of either vascular or functional origin seems to show an incomplete overlap between these two forms of depression. In patients classified as having major post-stroke depression, part of the symptomatology seems to be due either to the direct effect of the brain lesion or to the psychological reaction of the patient to the disabilities and handicaps provoked by the lesion.