A clinical study was performed on the respiratory cares of 1,654 critically ill patient who were admitted to the respiratory intensive care unit(RICU) from 1976 to 1980. This was 5.5% of the 25,191 patients in post-operative recovery room of Seoul National University Hospital. 1) The patients who needed respiratory care increased annually: 76 in 1979, 115 in 1977, 289 in 1978, 439 in 1979 and 735 in 1980 and their overall mortality was 14.5%. 2) Mortality in the respiratory intensive care unit(RICU) decreased annually and became 10.4% in 1980. 3) The duration of ventilatory assistance was the longest(11.1 days) for pediatric patients and 1.2 days for opend heart surgery patients. 4) Major causes of death (77cases) in respiratory care patients in the respiratory intensive care units were low cardiac output syndrome(33 cases), sepsis(14) and brain damage(7). 5) Types of airway in ventilatory assistance were orotracheal (508 cases) and tracheostomy (22 cases). 6) Importance of the monitorings including Swan-Ganz catheterizations, blood gases, measurements of colloid oncotic pressure and percutaneous gas measurements for critically ill patients in the respiratory cars unit were literarily discussed.