Today rapid medical and socio-economic progress has increased life expectancy and this has also increased the number of aged in the population. it is well known that the geriatric patient is generally considered to be a poor risk for anesthesia and surgery compared with the younger age group, because many have associated chronic systemic diseases in addition to the aging of physiological function. The purpose of this clinical study is to evaluate factors affecting complications and mortality in patients over 65 years of age during anesthesia and the postoperative period. Among 53,288 cases of total anesthesia performed from January 1970 to December 1979 at Severance Hospital, 1,097 cases over 65 years of age were reviewed. The results are as follows: 1) Anesthesia for geriatric patients over 65 years of age comprised 2.1% of total cases, of which the number of male patients(57.2%) was slightly greater than that of female patients (2.84%). 2) Overall mortality was 6.4%. 3) The mortality rate was related to preoperative physical status of patients: 2.7% of cases were elective and 21.3% were for emergency surgery. 4) high mortality rate following surgery was, in order of frequency, intrathoracic(11.1%), intracranial(11%) and upper abdomen(9.4%). 5) preoperative concomittant disease was, in order of frequency, hypertension(25.3%), chronic obstructive pulmonary disease(13.3%), pulmonary tuberculosis(12.1%) and anemia(9.9%). 6) The mortality rate was clearly proportional to anesthesia time. 7) General anesthesia(81.0%) was administered more often than regional anesthesia(19.0%). No direct relationship between the anesthetic agent and morthality rate was noted. 8) Common complications during anesthesia were hypertension(23.9%) and hypotension(19.4%). 9) The leading causes of mortality were respiratory complications(24.3%), cardiac failure (17.1%) and renal failure(17.1%).