Most patients, who will undergo risky surgical operations such as cardiac surgery or lung surgery, may have some knowledge on the surgical or anesthetic procedure involved in the operations. In order to understand the actual degree of patients' knowledge regarding anesthesia and to make anesthetic information available to the public more effectively based on this understanding, a questionnaire survey was conducted to 154 patients who had operations at the Yonsei cardiac center between June 1992 and January 1993. The questionnaire was composed of 21 questions; 19 multiple-choices and 2 askings for simple descriptive answers. The survey results analyzed by sex, age, education and occupation. The Chi-Square analysis is conducted to test the statistical significance among different groups in each category. The survey shows that first, most patients wanted to get anesthetic information at the practical common sense through mass media. Thus it is necessary to continuously provide detailed anesthetic information to the public through mass media. Obviously, it is more effective to provide anesthetic information to the public or patients adjusted to their educational level. Secondly, patients wanted to consult anesthesiologist about their own anesthesia before operations, and the informative preoperative visit by anesthesiologist have positive psychological effect to patients. Therefore, it is desirable for an anesthesiologist to give preoperative visit to a patient explaining complexities which may occur during and after anesthesia.