The ICU at Severance Hopital was opened with 7 beds on October 18, 1968 and expanded to 19 beds on February 2, 1981. From 1970-977, We statistically analyzed 3,072 ICU patients. During the period of years from March 1975 to February 1982, We have analyzed clinically 4,348 ICU patients. The Results were as Follows: 1) During the 7 years the total number of patients was 4,383. ln 1981, 1063 patients were admitted to the ICU: this number being almost twice that of in 1980. 2) During the 7 years, the overall mortality was 15.1%, highest in 1976(30.1%) and lowest in 1979(11.5%). It has decreased annually, 12.4% in 1980, 12.3% in 1981. 3) Total admission days in ICU were 18,148 days, the average patient stay in ICU being 4.17 days. The majority of the patients(81.2%) stayed in ICU less than 5 days. The number of patients staying in ICU more than 6 days increased every year from 14.2% in 1975 to 22% in 1981. 4) About 50% of the patients admitted were under the forties-age group. The number under the teens old group was 19%, this group representing the highest number of patients admitted to the ICU. The highest mortality(18.5%) occurred in the 1 to 10 yearold-age group. 5) The number of patients admitted to the department of internal medicine was 1,574 cases, which was the highest among all departments. The mortality rate was highest in the neurosurgery department(41.9%). In 1981, the number of ICU patients in cardiac surgery and pediatrics was increased three time compared with that of 1975. 6) All ICU patients have been divided into two categories, operative and non-operative cases. The operative cases were 2,150, non-operative cases 2,198 cases. Mortality rate was 10% in operative cases, 20% in non-operative cases. 7) Case expired from march 1981 to February 1982: The number of expired parients including those with a poor prognosis was 183 cases. The number of patients that expired under the 10-year-age group was the highest, 78 cases. The cases that expired in internal medicine and pediatrics were 63 and 58 cases respectively. The causes of death were due to damage of central nervous system, cardiovascular system, respiratory system in that order. From the above results, it can be concluded that in spite of an increase in patients, the mortality rate has decreased annually.