This article reviewed the thoretical unerpinnings of the DSM III classification system, with particular emphasis on psychogeriatic practice. Advantages of a descriptive approach, use of operational criteria, and the utility of a multiaxialsystem in developing comprehensive treatment program were examined. A retrospective study, 5 years after the implementation of DSM III, was conducted on all consecutive admissions to the neuropsychiatry department of Ewha Womans University, College of Medicine, and the results were as follows. The thirty cases of the senile mental disorders showed the following characteristic pictures. 1) Majority of the cases(53.4%) were distributed in the decade of their sixties and male. 2) In the diagnostic distribution, 53.4% of the cases were categorized as organic mental disorder and 30.0% as major affective disorder. 3) The ratio of male patient and female patient was 4.3:1 in organic mental disorder and 2:1 in major affective disorder. 4) In the age distribution, 50.0% of the cases were categorized as organic mental disorder and 55.6% as major affective disorder. Both of the cases were aged between 60 and 64. 5) Their educational level revealed that 40.0% of the patients were primary school graduates. 6) As to the occupational distrubution, the jobless occupied the larger percentages, but patients who have job their age distribution was 60-64. 7) As to their religious affiliation the most population was 30.0% of protestant. 8) In the distribution of physical disorders, hypertension occupied the highest rate of 26.7%. 9) As to the marital status, 73.3% of the cases were living with their spouses. 10) There were no relation between premorbid social psychological stress and premorbid adaptation.