Until several years ago it was generally agreed that anihypertensive medication should be stopped a few weeks before anesthesia and surgery in order to regain the compensatory function of cardiovascular system during anesthesia and surgical stress. However the present concept is that the better the hypertension is controled the more the patient's chances of surving anesthesia and it is recommended that antihypertensive medication should be continued to the time of anesthesia. The authors have experienced cases of hypertensive patients undergoing various kinds of operation and have-analyzed these cases according to the degree of hypertension, sex, department, anesthetic agent and technique, previous anesthetic medication, abnormal ECG finding and arterial blood pressure changes after anesthesia, at Jeonbug National University Hospital from January 1977 to June 1979. The results were as follows: 1) The number of hypertensive cases was 326 (12.3%) out of 2664 total patient who received various surgical operations. 2) Only a few patients(16cases, 0.5%) received antihypertensive medication before surgery. 3) The degree of hypertension was mostly class 1 or 2(274 patients, 78%) according to the severity index of Elwood 4) Most of the patients (253 cases, 74%) revealed elevated blood pressure after induction of anesthesia.