The authors made a clinical study on the changes of cardiovascular functions according to duration of inhalation anesthesia as compared with the preanesthetic status in 250 adults aged from 20 to 50 years who were anesthetized for operations by the Department of Anesthesiology, Pusan National University Hospital from September, 1981 to August, 1982. The results obtained were summarized as follows: 1) There were marked increases in pulse rate 5 minutes after the start of anesthesia in all groups and this change persisted until 30 minutes after anesthesia. Of all groups, the ethrane group(group3) showed the most marked increase in pulse rate 5 minutes after the start of anesthesia. 2) Diethyl either group (group5) showed the greatest change of systolic blood pressure and this lasted until 30 minutes after anesthesia. 3) The halothane (group 1,2) showed variable changes in electrocardiographic patterns. Biphasic T waves appeared more in the ethrane group (group 3,4) and the fewest changes in EKG were observed in the diethyl ether group(group5).