Events during and after anesthesia were checked in order to evaluate intraoperative death which were related to anesthesia factors. 114 events occurred among the 4, 268 anesthetics at St. Mary's Hospital during the period of May 1975 to October 1976. Some of these events may occur due to malhandling of the anesthesia machine, misuse of drugs, incorrect technics, anesthetist fatigue, misunderstanding of proper knowledge)and negligent actions. Rarely, some of them may become critical and unexpected pitfalls in anesthesia. Like other physicians, anesthesiologists are responsible for their acts. They are also accoun table as physicians for making the decision as to what they describe and administer,and how they prescribe and administer. In general, a physician must perform his work in accordance with accepted medical practice, with the standards current in the community, and he must bring to the task a resonable degree of skill and knowledge and he must exercise resonable care. When any of these principles are abrogated then negligence may exist. The anesthetist is liable if he fails to take those steps to satisfy himself that all is correct and those steps which a careful and prudent anesthetist would ordinarily take. For the anesthesiologists sake, 114 events were evaluated and conclusions were as follows; 1. 114 events occurred among the 4,268 anesthetics and the incidence was 2.7%. 2. There are variable events as slight as lip trauma, and as severe as cardiac arrest. 3. Preventable events were 87 cases out of 114 cases, and the incidence was 76. 3%. 4. Anesthesiologists must use careful management of the patients with correct knowledgement and skillful technic through the preanesthetic and postanesthetic periods.